Lecture Materials
Week 3
For the full set of Lecture Notes for Topic 3A, please click on the PDF file below.
ToD_full.pdf
PDF File
For the full set of Lecture Notes for Topic 3B, please click on the PDF file below.
Blood_full.pdf
PDF File
Quote
"Death may be the greatest of all human blessings."- Socrates (469 - 399 BC)
Learning Objective(s)
At the end of this topic, you should be able to:
3A. Time of Death
1.
2.
3.
4.
5.
Differentiate Algor Mortis, Rigor Mortis, and Livor Mortis;
Illustrate how circumstantial evidence can be useful;
Describe the states of putrefaction;
Explain how forensic entomology can help determine time of death;
Summarize the techniques used for dating old bones;
3B. Blood
1.
2.
3.
4.
Explain blood biochemistry and blood typing;
Describe the methods used in the identification and individualisation of blood;
Identify the various blood spatter patterns;
Conduct blood spatter analysis to find the source of blood and reconstruct past
events.
Synopsis
3A. Time of Death
Physiological changes in the body after death will be surveyed, and concepts
such as Algor Mortis, Rigor Mortis, and Livor Mortis will be introduced. There will
also be a discussion on putrefaction and how forensic entomology can be applied
to forensic science. Techniques used for dating fresh and old bones will be
examined. Case studies will be used to demonstrate the application of the
techniques and concepts taught in this lecture.
3B. Blood
Blood chemistry and the scientific basis of blood typing will be discussed. There
will also be a review of the tests which can be carried out to identify and
individualise blood. Blood spatter patterns and the deduction of information from
the types of spatter patterns will be examined. Several case studies will be used
to illustrate the concepts and techniques taught in the lecture.
Case Studies
Peter Thomas; Danielle van Dam; Piltdown Man; Peter Reyn-Bardt; The Bog
People - Grauballe Man & Lindow Man; Ötzi; Christopher Nudds; Lord Lucan
Week 3A - 1 Recent Deaths
[MUSIC]
Let's suppose a body has been found.
One of the most important pieces of information to get
is to find out how long that person has been dead.
This is of great importance for
reconstruction of the sequence of events that led up to the incident.
Play video starting at ::47 and follow transcript0:47
And if this is a murder, then of course, you want to
compare that time of death to the known movements of whoever the suspects are.
Play video starting at ::58 and follow transcript0:58
Well, what we're going to do is look at some of the different techniques that
can be used.
Starting off with bodies that have died very, very recently.
So what happens at death?
Well, the first thing of course is the body goes limp.
That's because your muscles are under tension when you're alive because your
brain is telling them
to do so.
When your brain stops telling your muscles to be tense, they go limp,
Play video starting at :1:26 and follow transcript1:26
and then all the biochemical machinery that's going on inside you and
is keeping you alive
grinds to a halt.
Play video starting at :1:34 and follow transcript1:34
One of the things that
that machine is doing is maintaining your body temperature.
You are burning fuel that you get from your food in order to
maintain your temperature at the correct level.
That comes to a stop and that means that your body will start to cool down.
This phenomenon is called Algor Mortis,
and is one of the most important methods for estimating time of death.
Play video starting at :2:1 and follow transcript2:01
However, these estimates should always be done by someone who is experienced in
this kind of work, because the rate at
which your body cools can be affected by all sorts of different factors.
One factor is the size of the body.
A thin person is going to cool down much faster than a fat person,
Play video starting at :2:22 and follow transcript2:22
and that is simply a reflection of the surface area to volume ratio.
Play video starting at :2:28 and follow transcript2:28
The location in which the body is placed is going to make a big difference.
If it's out on a hillside with the wind blowing over it,
it's going to be cooling down faster than if it's locked in a trunk or a bag.
Play video starting at :2:42 and follow transcript2:42
The amount of clothing will obviously affect it.
A naked body or a body wearing just t-shirt and shorts is going to
cool faster than one that's buttoned up in a thick, heavy winter overcoat.
Play video starting at :2:56 and follow transcript2:56
And of course, the weather will have an effect.
If the body is out in cold weather with the cold wind blowing and blowing and
the rain falling,
it will cool down faster than on a hot day in the sunshine.
Play video starting at :3:12 and follow transcript3:12
In addition to these environmental factors, it’s also important to
make sure you measure the correct body temperature.
Play video starting at :3:19 and follow transcript3:19
Obviously, the skin will feel cool after a relatively short time,
again depending on environmental factors.
Play video starting at :3:28 and follow transcript3:28
But even when we consider internal organs for
measuring the temperature, we have to get it right.
The brain, for instance, it has very little insulation from the outside elements,
which means that the brain will cool down distinctly faster than internal organs,
Play video starting at :3:46 and follow transcript3:46
and it's those internal organs which should be measured because
they will give you the most representative temperature.
And one example would be to measure the liver temperature.
Play video starting at :3:58 and follow transcript3:58
Well, all things being considered, if we assume it's an average, normal set of
circumstances, then we can come up with a general rule that the body
will cool down at a rate of about 1 to 1.5 degrees Fahrenheit per hour.
Play video starting at :4:15 and follow transcript4:15
And this will continue until the temperature of the body gets down to
ambient temperature and then obviously, it will stop cooling down.
Play video starting at :4:23 and follow transcript4:23
In fact, it may even start to warm up,
because after a few days, the heat generated by the process of
putrefaction may actually cause the temperature to start increasing again.
Play video starting at :4:37 and follow transcript4:37
We'll talk about putrefaction in a short time.
Play video starting at :4:42 and follow transcript4:42
In addition to Algor Mortis,
there's also the very well known phenomenon of Rigor Mortis.
Play video starting at :4:49 and follow transcript4:49
Now, when you die, your brain stops sending signals to your body to do stuff,
but that doesn't mean chemical activity in your body stops.
Play video starting at :5: and follow transcript5:00
And the cause of Rigor Mortis is the continuing chemical action in
your muscles, and it causes them to stiffen soon after death,
and then after further time, that stiffening disappears.
It's a chemical action within the muscles.
Play video starting at :5:17 and follow transcript5:17
It doesn't happen uniformly over the whole body.
It appears first, for instance, in the jaw, spreads to the arms and
then to the legs.
So, it will be complete over the body in maybe 12 hours’ time and
then it will gradually disappear again.
Play video starting at :5:35 and follow transcript5:35
Once again, this needs an experienced expert in the field to
assess the state of Rigor Mortis in the body in order to give the estimate.
Play video starting at :5:49 and follow transcript5:49
A third method, not so
well known, is Liver Mortis, also known by a number of other terms.
Play video starting at :5:57 and follow transcript5:57
Now, Livor Mortis is due to gravity.
Play video starting at :6: and follow transcript6:00
You consider your blood.
Your blood consists of all sorts of materials including the red blood cells,
and it's maintained roughly homogeneous and
in continuous motion during life by the action of the heart.
Play video starting at :6:16 and follow transcript6:16
On death, the heart stops, and then the effects of gravity start to
be felt by the red cells, and they settle out to the lower parts of the body.
Play video starting at :6:28 and follow transcript6:28
If, for instance, the body is hanging by the neck,
then the red cells will settle into the legs or the lower parts of the legs,
and a distinct discolouration will be seen down there in the legs.
Play video starting at :6:42 and follow transcript6:42
Now, if the body is lying on the ground, it's not quite so simple.
Obviously, the red cells will settle down towards the side of
the body that is against the ground, under the influence of gravity.
Play video starting at :6:57 and follow transcript6:57
You have the body temperature starting out at normal body temperature and
dropping gradually to ambient, maybe going up again afterwards.
You have the Livor Mortis and Rigor Mortis appearing,
gradually up to reach their maximum, and then both fading away;
Play video starting at :7:15 and follow transcript7:15
and all of these require an estimate from an experienced expert.
Play video starting at :7:21 and follow transcript7:21
And of course it's a problem.
This relies on an expert giving his opinion,
it's not a rigorous scientific method.
So a lot of research has been done on trying to develop more scientific,
and hopefully more precise methods.
Play video starting at :7:39 and follow transcript7:39
One of the suggestions is to use ocular potassium,
and that is the potassium that's present inside the eye in
the vitreous humor of the eye.
Play video starting at :7:51 and follow transcript7:51
The concentration of potassium in the eye
is lower than the concentration of potassium in the rest of the body,
and your biochemical machinery makes sure
that this concentration differential is maintained during life.
Play video starting at :8:7 and follow transcript8:07
After death, that machinery is no longer operating, so
potassium from the rest of the body will gradually diffuse into the eye
and the potassium content of the eye will gradually increase.
And it's been suggested that this is a good way of measuring the time of
death, relatively free from environmental factors.
Play video starting at :8:31 and follow transcript8:31
We can also use circumstantial evidence.
Circumstantial evidence typically won't give you the time of death, but
it gives you a time when that person was still alive.
Play video starting at :8:42 and follow transcript8:42
For instance, if at autopsy, the stomach and intestine contents are examined,
you can get an estimate of the time of the person's last meal.
Play video starting at :8:54 and follow transcript8:54
For instance, the stomach empties in about two hours,
so if the stomach is empty,
then you know it's at least two hours since that person had a meal.
Play video starting at :9:7 and follow transcript9:07
Technology is helping.
Play video starting at :9:11 and follow transcript9:11
You can look at someone's watch.
Play video starting at :9:13 and follow transcript9:13
Now, normally of course, a watch will not stop when a person dies, but
suppose this is a drowning case
and it's a cheap watch.
In that case, the water will cause the watch to stop and
you'll have a good timing of when the person went into the water.
Play video starting at :9:31 and follow transcript9:31
Mobile phones are very useful.
If you think about it, when was the last time you used your mobile phone?
Wasn't very long ago, was it?
Play video starting at :9:42 and follow transcript9:42
So, in the picture you see Dr. Nathaniel Cary, and this is a quotation from him.
He said, "Nowadays, last use of the telephone can be terribly important." And
he had been testifying in the trial of a man called Steven Wright,
who was convicted of the murder of several women in a short period of
time just before Christmas, 2006.
And using the mobile phone records, they were able to estimate time of death.
Because when you use your mobile phone, it shows you're still alive,
and the time of that phone call is recorded by the telecoms company, and
this is going to be an increasingly useful method.
Week 3A - 2 Decomposing Bodies I
(Putrefaction)
[MUSIC]
So what do we do if the body that we found has been there for several days, and
it's already cooled down to ambient temperature, and the
Livor Mortis and the Rigor Mortis have both passed?
Well, probably what we would have to do at this stage
is to look at the state of putrefaction of the body,
and once again, this needs an experienced person
to make a judgment and give his opinion.
Play video starting at ::44 and follow transcript0:44
So what is putrefaction and how does it happen?
Well, when you're dead, of course, you're dead, but all the microorganisms
that live inside you, they're not dead, and they keep on going
and they will start to eat you.
Play video starting at ::59 and follow transcript0:59
Essentially they will take your tissues and they will
break them down chemically and use them as nutrition.
But as a by-product, they will produce all
sorts of chemicals, including gases and volatile chemicals,
and it's these chemicals produced by putrefaction that
give an abandoned dead body its particular smell.
And if you've ever walked past a ditch where
there's a dead dog, you know what I mean.
Play video starting at :1:27 and follow transcript1:27
So, an experienced examiner can look at the body and make a judgment.
Of course, he does have to take into
effect all sorts of environmental factors, particularly temperature.
If it's a very hot place, rather than a very cold place,
then of course, there's going to be a big difference in the rates.
Play video starting at :1:47 and follow transcript1:47
You also get effects due to drug use, because
if someone has been a heavy drug user, the
presence of all those drugs in their body can
affect the rate of which the microorganisms do their stuff.
And again, this relies on experience.
Play video starting at :2:3 and follow transcript2:03
So, one of the problems is there's not many hard
scientific studies on the rate of decomposition of human bodies.
So, some studies are ongoing.
One of them is, as you see, at the University
of Tennessee, Knoxville, where they have a so-called "Body Farm",
which is an area of open ground which they fenced
off, and they will place donated bodies in particular situations clothed or unclothed, partially buried, etc. and then they can scientifically observe the process of putrefaction,
and maybe this will make estimates more scientifically reliable.
Play video starting at :2:44 and follow transcript2:44
Well, during putrefaction, this is roughly what happens.
After a few days, the body will start to discolour and also it will start to swell.
The reason for the swelling is the gases produced by
the putrefaction process are inflating the body slowly, like a balloon.
Play video starting at :3:4 and follow transcript3:04
As the days go past, the staining spreads and the veins of
the body start to become discoloured as the materials in your blood decompose.
Play video starting at :3:16 and follow transcript3:16
Further days pass, the abdomen swells even more
as more gas is developed by the putrefaction process.
The skin starts to blister, and eventually the abdomen will
become very tight and swollen because of all the gas inside.
Play video starting at :3:34 and follow transcript3:34
The tissues also break down, so the tissues
lose their structural integrity, and they start to soften.
And that means that the organs and cavities inside the body, which have
been filled with these putrefaction gases,
then burst, a little bit like balloons.
In addition, the fingernails will no longer be
attached to the fingers and they will fall off.
Play video starting at :3:59 and follow transcript3:59
So in a typical case, maybe in four
weeks, the soft tissues will be starting to liquefy,
and one of the consequences of this
is that the face is no longer recognizable.
So if the body is found at this stage, somebody just looking at it
can't tell who it is, and it will have to be identified by other means.
Play video starting at :4:21 and follow transcript4:21
So, a body exposed to the elements will ultimately turn into a skeleton.
How long this takes is very dependent on environmental factors, so
some people in some places might say it takes several years.
Here in hot, tropical Singapore, it can take
as little as two weeks for that to occur.
Play video starting at :4:44 and follow transcript4:44
Now, not all bodies putrefy.
If the environmental conditions are right,
particularly if the conditions are extremely dry,
then the body will become mummified and the tissues will actually be preserved.
So mummification does happen by accident because
the body happens to be in those circumstances.
But of course, the most famous kinds of
mummification is where it has been done deliberately.
So these four gentlemen in the slide here were all mummified.
Play video starting at :5:18 and follow transcript5:18
There's Pharaoh Ramses the Second of Egypt.
Play video starting at :5:23 and follow transcript5:23
This is Lenin, the founder of Communist Russia,
who was mummified and preserved by having a
secret chemical injected into him after his death,
and his body is still there in Moscow.
Play video starting at :5:38 and follow transcript5:38
If the Russians did it, then of course the Chinese did it.
So there's Chairman Mao.
Play video starting at :5:43 and follow transcript5:43
And the last of these four
gentlemen actually specifically wished to be mummified,
and he said so.
And he is Jeremy Bentham,
the English philosopher who was also the
founder of University College London, and if you
go to University College London, you can go and see him there, he's still there.
[BLANK-AUDIO]
Week 3A - 3 Decomposing Bodies II
(Forensic Entomology)
[MUSIC]
An additional technique for bodies that are in this
stage is to use what is called forensic entomology.
Entomology is the study of insects.
So, how can we use insects to determine the time of death?
Well, our dead body is lying somewhere outdoors and it's
starting to smell and it's detected very, very quickly by insects,
and the females, of course, are always looking for a good place
to lay their eggs, and there's nowhere better than a dead body.
They can lay their eggs on the dead body; when the
eggs hatch, their children come out, that's the maggots, then their
children are assured of a really good supply of food, so
that they can develop and produce the next generation of blowflies.
Play video starting at :1:7 and follow transcript1:07
The life cycles of these creatures are usually fairly regular.
So if you can find a maggot off the corpse, and you can estimate
how old that maggot is, you've got a good estimate of the time of death.
Play video starting at :1:21 and follow transcript1:21
But it has to be done right,
because each kind of insect has it's own life cycle, with it's own timing.
The first thing you have to do is to know the species.
Play video starting at :1:33 and follow transcript1:33
This is not so easy from a maggot.
So, what is typically done is that the maggots are collected from the body, from
the corpse, they are taken back to
the laboratory and they are reared to adulthood.
When you have the adult it is much easier to identify the species.
Play video starting at :1:50 and follow transcript1:50
When you identify the species, then of course, you know what the life cycle is.
Play video starting at :1:57 and follow transcript1:57
So, when you take your maggot back to the laboratory and you rear it
to adulthood, you also time how long it takes to reach the adult stage,
and then you can back calculate, from the length of
the life cycle, how long it had been on the body.
Play video starting at :2:14 and follow transcript2:14
So here, for instance, is the life cycle of the blowfly.
It starts out as an egg, the egg hatches to give a little maggot called the 1st
Instar, then it changes to the bigger 2nd Instar, and then the third Instar maggots.
And then when they are fed sufficiently, they will
turn into a pupa and they will undergo their metamorphosis,
and they will emerge as the adult and
the life cycle of the blowfly has gone round once.
Play video starting at :2:43 and follow transcript2:43
Sometimes this technique is very, very powerful.
An example comes from this case, from back
in 1964, involving a man called Peter Thomas.
Play video starting at :2:54 and follow transcript2:54
In this case, some boys had gone down to the local
woods because they wanted to collect worms so they could go fishing.
And they found more than worms.
They found the dead body of Peter Thomas absolutely covered in maggots.
So of course, the police came, and the police looked at the body,
and they thought that it had been there for maybe six to eight weeks.
But a forensic expert, Professor Keith Simpson, was called in.
And Simpson took a look, and he took a look at the maggots,
and he disagreed with that six to eight week estimate
and he said, "At least nine or ten days, not more than 12 days."
And when they did the back calculation, that works out
as June the 16th or June the 17th of 1964,
and these dates proved to be extremely important during the prosecution.
Now, the police had identified a suspect in
the case, and this was a man called William
Brittle who had had some financial dealings with Peter
Thomas, and there was some bad result from this.
So it was suspected that Brittle had murdered
Thomas in some kind of dispute over money.
Play video starting at :4:11 and follow transcript4:11
So when this went to trial, one of the issues was the time of death.
Play video starting at :4:18 and follow transcript4:18
Keith Simpson has said that Thomas was dead on June the 16th or June 17th.
Play video starting at :4:24 and follow transcript4:24
Very importantly, Brittle had no alibi for that time,
but he had a good alibi for dates after that.
Play video starting at :4:34 and follow transcript4:34
Well, the defense came up with three witnesses who claimed they had
seen Peter Thomas alive and well on June the 20th or 21st,
several days after Simpson says he's dead.
Play video starting at :4:47 and follow transcript4:47
So here on one hand, you have the maggots.
On the other hand, you have the eyewitnesses.
Play video starting at :4:53 and follow transcript4:53
But the defense went a bit too far,
they called their own entomologist
Play video starting at :5: and follow transcript5:00
and they asked their own entomologist to testify based on the maggot evidence.
And that's where it went wrong for the defense, because their expert turned out
to agree with Simpson, saying the man was dead on the 16th or the 17th.
Play video starting at :5:16 and follow transcript5:16
Well, who're you going to believe?
Are you going to believe the eyewitnesses, or are you going to believe the maggots?
Well, in this case, the jury preferred
to believe the maggots, not the eyewitnesses.
Play video starting at :5:30 and follow transcript5:30
On the other hand, forensic entomology can also let you down.
Play video starting at :5:35 and follow transcript5:35
Let's look at the case here of a young girl
called Danielle van Dam who was murdered back in 2002.
She was about 7 years old.
So she was last seen alive by her parents on the
evening of February the 1st, when her mother put her to bed.
Play video starting at :5:54 and follow transcript5:54
The next morning, she was missing.
So from February the 2nd she had disappeared.
Play video starting at :6:1 and follow transcript6:01
Suspicion fell on a man called David Westerfield who lived nearby,
and he had gone off on a trip into the desert.
This is in California,
he'd gone off into the California desert in his RV for
a few days, and only came back home on February the 5th.
Play video starting at :6:19 and follow transcript6:19
As soon as he came back,
he was essentially placed under police surveillance.
So from February the 5th, the police were watching him, and you
really can't get a better alibi than being watched by the police.
Play video starting at :6:33 and follow transcript6:33
It took a long time for Danielle's body to be found.
It was finally found on February the 27th, so
Play video starting at :6:42 and follow transcript6:42
this is more than three weeks after her disappearance.
It was up in the California mountains.
Obviously by this time badly decomposed,
and also, it had been attacked by animals, maybe coyotes or something.
Play video starting at :6:57 and follow transcript6:57
In fact, one of the ways they had to
use to identify the body was to fingerprint it.
So the fingerprint, even though the tissues were decomposing, they
were able to get a fingerprint off the skin of the finger.
Play video starting at :7:14 and follow transcript7:14
Now a key question was, when did Danielle
die? When was her body dumped in the mountains?
Play video starting at :7:22 and follow transcript7:22
Well, here's the calendar of January and February,
Play video starting at :7:27 and follow transcript7:27
and they consulted a number of experts, particularly forensic
entomologists, to get estimates of when her body was placed in the mountains.
And what I've done here is to highlight in red those few days from February
the 2nd to the 5th, when David Westerfield was on his trip to the desert.
Play video starting at :7:49 and follow transcript7:49
So the first expert made this estimate here, that the
body had been there since the second half of January.
Well, of course this is impossible because, as you know,
Danielle was tucked in by her mother on February the 1st.
Play video starting at :8:8 and follow transcript8:08
This expert conceded that maybe he could stretch the dates through into
the first week of February, which includes the time of Westerfield's desert trip.
Play video starting at :8:21 and follow transcript8:21
A second expert, looking at the entomology, put it from the
12th to the 23rd of February, basically the second half of February
which is time when Westfield was under police surveillance.
Play video starting at :8:36 and follow transcript8:36
The third expert, a slightly earlier time frame,
but still during that period of police surveillance.
Play video starting at :8:43 and follow transcript8:43
The fourth expert pinned it down to a few days,
again, it's in middle February.
Play video starting at :8:52 and follow transcript8:52
And another expert, again, the late part of February.
Play video starting at :8:57 and follow transcript8:57
So when you see five experts in the same area giving estimates that are so
widely varying, this does not lend very much credibility to the subject.
And so the investigators, of course,
also consulted medical examiners, and the medical
examiners gave this estimate here, from the first of February to late February.
So, as I said at the very beginning, it's very difficult to give a
very accurate estimate, and that's why the range they've estimated here is so big.
Play video starting at :9:38 and follow transcript9:38
So, what went wrong?
Why is it that the entomologists' estimates are all over the place?
Play video starting at :9:44 and follow transcript9:44
Well, there are other variables that have to be taken into account.
One thing is the weather.
Play video starting at :9:50 and follow transcript9:50
This is up in the mountains.
The weather in the mountains can be very variable.
So maybe the weather at the weather station, which was some miles
away, was somewhat different from the weather where Danielle's body was left,
and therefore it's not possible to make an accurate estimate.
Play video starting at :10:9 and follow transcript10:09
There's also the possibility of micro-climates.
Play video starting at :10:13 and follow transcript10:13
Anyone who's been in the mountains knows that the south
facing side of the mountain, the weather is quite different,
it's distinctly warmer to the north side of the mountain.
And in fact, in mountainous country, you'll only have to
go a few hundred metres and you can experience these changes.
Play video starting at :10:32 and follow transcript10:32
Another factor is whether the body was covered or not.
If the body had been covered, then it
would delay when the insects would find it,
Play video starting at :10:42 and follow transcript10:42
and this was never really resolved.
Play video starting at :10:44 and follow transcript10:44
And then again, of course, there is the possibility that actually
David Westerfield is innocent and that the entomologists have got it right.
Well, in the end, David Westerfield was found guilty
and he was sentenced to death by lethal injection,
and at the time of recording, he is still
in prison awaiting that sentence to be carried out.
Play video starting at :11:8 and follow transcript11:08
So presumably, the jury believed the evidence of the
medical examiners and discarded the opinion of the entomologists,
Play video starting at :11:17 and follow transcript11:17
and they also considered other evidence such
as the fingerprints, some blood spots, and
the hair from the van Dam family dog in the Westerfield RV as indicating guilt.
Play video starting at :11:31 and follow transcript11:31
But the story very clearly illustrates that making
these estimates can be very, very difficult indeed.
[BLANK_AUDIO]
Week 3A - 4 Analysis of Skeletal
Remains I
[MUSIC]
Play video starting at ::18 and follow transcript0:18
Ultimately the body is going to turn into a skeleton.
And once it's a skeleton it's very difficult to get good information
because bones after all are bones.
Play video starting at ::31 and follow transcript0:31
One test that can be done is to look at fluorescence.
Play video starting at ::35 and follow transcript0:35
Fresh bone will fluoresce under UV light.
Old bone, maybe more than a hundred years old bone will no longer fluoresce.
Play video starting at ::46 and follow transcript0:46
And this is very useful because if bones turn out to be more than a hundred years
old, then you can be pretty safe in assuming that anyone associated
with that event is also going to be dead by this time.
Play video starting at :1:1 and follow transcript1:01
You can do some analysis to get some more information.
What we can do is use techniques of elemental analysis to measure the level
of specific elements in the bone and this can enlighten us a little more.
Play video starting at :1:18 and follow transcript1:18
This is typically called FUN analysis after three elements,
fluorine, uranium, and nitrogen.
Play video starting at :1:27 and follow transcript1:27
Now fresh bone contains proteins.
Play video starting at :1:32 and follow transcript1:32
All proteins contain the element nitrogen.
Play video starting at :1:37 and follow transcript1:37
And in fresh bone, if you analyze it,
you will find that bone is about 4% nitrogen by weight.
However, let's suppose the body is in a grave or
somewhere, exposed.
The proteins in those bones will gradually break down with time.
Play video starting at :1:57 and follow transcript1:57
But as the protein molecules break down, the nitrogen containing compounds will
diffuse out of the bone into the environment and be lost.
Which means that the bone nitrogen content will decrease with age.
Play video starting at :2:13 and follow transcript2:13
Now, let's turn to the upper two elements, fluorine and uranium.
These two elements are not naturally present in bone, so
the content of these two elements in fresh bone is 0%.
There shouldn't be any fluorine or uranium in your bones.
Play video starting at :2:32 and follow transcript2:32
Now suppose those bones are buried in an area where
the groundwater contains appreciable amounts of those elements,
okay, they would be leaked from the local rocks.
Play video starting at :2:48 and follow transcript2:48
Then, the bones will absorb those elements from the environment.
Play video starting at :2:53 and follow transcript2:53
And that means that the concentration of fluorine and
uranium will increase with time.
Play video starting at :3: and follow transcript3:00
Now, you cannot use this as a kind of clock to determine time of death,
because the absorption of these elements depends on their presence
in the local environment.
Play video starting at :3:11 and follow transcript3:11
So if that body is in a place where the local geochemistry means there is no
uranium, then of course it will not absorb any uranium however long you leave it.
Play video starting at :3:23 and follow transcript3:23
But if it's in an area where there is uranium naturally present
as a trace mineral in the rocks, then you will get uranium absorption.
Play video starting at :3:32 and follow transcript3:32
So you can't use it as a clock, but
you can use it to compare two bones from the same place.
Play video starting at :3:39 and follow transcript3:39
And if those two bones have been in the same place for
the same length of time, the same number of centuries maybe,
then they should have the same amount of uranium and fluorine.
Play video starting at :3:52 and follow transcript3:52
Here's an example where this kind of analysis proved critical, and
this is the story of Piltdown Man.
Play video starting at :4:1 and follow transcript4:01
If we go back about 100 years or a little bit more,
one of the great scientific challenges was finding the ancestors,
our own ancestors, the ancestors of homosapiens.
Play video starting at :4:15 and follow transcript4:15
Now the Germans had found the remains of ancient humanoids.
Play video starting at :4:20 and follow transcript4:20
And this is Neanderthal Man.
Play video starting at :4:23 and follow transcript4:23
The French have found the remains of ancient humanoids as well.
And this is Cro-Magnon Man.
And since then of course we also have Peking Man and Java Man.
And all the discoveries in East Africa.
Play video starting at :4:38 and follow transcript4:38
But 100 years ago, British paleontologists were very disappointed because they had
not been able to find any ancient humanoid remains anywhere in Britain.
So they had nothing to compare with the remains found by the Germans and
the French.
Play video starting at :4:59 and follow transcript4:59
Well, one dig that was going on was at a place called Piltdown.
It's a little way outside London.
And this was during the period 1912 to 1915.
And alongside many, many bones of prehistoric animals,
they also found two fragments of humanoid bone and
they claimed that these were approximately 500,000 years old.
And so of course they went to the Natural History Museum in London and
they were displayed in private place.
Now what they'd found was two fragments of bone, and
you can see the reconstruction in this picture here.
What they found is the two dark parts.
You can see a skull fragment, and you can see a jaw fragment.
Play video starting at :5:50 and follow transcript5:50
When you look at these fragments,
you conclude that the skull fragment is very similar to a modern human.
Whereas the jaw fragment is more similar to a modern ape,
which indicates that in evolutionary terms,
our brain case evolved before our jaw evolved.
Play video starting at :6:11 and follow transcript6:11
And this finding was never completely accepted by the community.
Because the more favorite theory was the jaw evolved in advance as the brain.
Play video starting at :6:22 and follow transcript6:22
Nevertheless, both bone fragments were there in
the Natural History Museum until the late 1940s.
By the late 1940s, chemical techniques have improved a lot and someone had
the courage to go to these bone fragments and do a little bit of chemical analysis.
In fact, he analyzed them for fluorine and nitrogen, and this is what they found.
Play video starting at :6:48 and follow transcript6:48
The skull fragment turned out to be 0.2% fluorine, whereas the jaw
fragment had essentially no detectable fluorine, or almost no fluorine.
Play video starting at :7:1 and follow transcript7:01
That means that the two pieces of bone
had not been in that site at Piltdown until for
the same length of time, therefore they could not come from the same individual.
They had to come from different individuals.
Play video starting at :7:15 and follow transcript7:15
What's more, the jaw fragment turned out to contain almost 4% nitrogen,
which meant that the jaw fragment must be essentially a modern piece of bone.
Play video starting at :7:27 and follow transcript7:27
Well, it turned out that,
that jaw fragment actually have been taken from a modern orang-utan.
Whereas the skull fragment was human, and it was a few centuries old.
And it was a hoax.
Someone had acquired these two bone fragments, had chemically dyed them so
that they're the dark color that you see in the picture, and therefore look old.
And that person had placed them in the excavation, so
that they would be found by the paleontologists.
Play video starting at :7:57 and follow transcript7:57
Well, it's never been proved who did it.
There are suspicions about who might have done it, but of course,
after this length of time, it's never been proved.
But Piltdown man stands as one of the most famous examples of a scientific fraud.
But it's a scientific fraud that's been exposed by chemical analysis.
Week 3A - 5 Analysis of Skeletal
Remains II
[MUSIC]
What if the human remains that have been found are really old?
What technique can we use for dating them?
The answer is a technique called carbon-14 dating.
Play video starting at ::31 and follow transcript0:31
Now, the element carbon is ubiquitous in living organisms,
Play video starting at ::35 and follow transcript0:35
it's the basis of all life on Earth.
Play video starting at ::39 and follow transcript0:39
Now, carbon comes in three forms.
By far, the most common is carbon-12,
this is the isotope carbon-12.
So in carbon-12, the nucleus of the atom is made up
of 6 protons and 6 neutrons, and it's a quite stable nucleus.
Play video starting at ::58 and follow transcript0:58
A very small amount of carbon is carbon-13,
and in carbon-13, the nucleus of the atom
is made up of six protons and seven neutrons,
and again, this is a perfectly stable atom.
Play video starting at :1:13 and follow transcript1:13
But there's a small amount of carbon-14,
and in carbon-14, the nucleus is made up of six protons and eight neutrons
and this is an unstable nucleus.
That means carbon-14 is radioactive.
Play video starting at :1:30 and follow transcript1:30
And if you have a sample of carbon which contains 12, 13, and 14,
gradually, slowly over time, that carbon-14 will decay and disappear.
Play video starting at :1:44 and follow transcript1:44
Now, radioactive decay occurs at a very fixed and regular rate,
and for carbon-14, we know what the rate is and
we measure that the rate by the so-called half-life.
A half-life is the time it takes for half
the atoms in your sample to undergo radioactive decay.
For carbon-14, that is just over 5000 years,
Play video starting at :2:10 and follow transcript2:10
so in 5000 years, half your carbon-14 will disappear.
In another 5000 years you'll be down to a quarter, and another 5000
years down to an eighth, and so on and so on and so on.
Play video starting at :2:23 and follow transcript2:23
Now, how can we use this for dating?
Play video starting at :2:27 and follow transcript2:27
The key assumption is, the amount of carbon dioxide
which is carbon-14 in the atmosphere is approximately constant.
Play video starting at :2:38 and follow transcript2:38
The carbon-14 is produced by the
bombardment of the atmosphere by cosmic rays.
As long as the bombardment by cosmic rays is constant,
then the formation of carbon-14 is going to be constant.
Now where does the carbon-14 go?
It's present in the atmosphere in carbon dioxide.
Play video starting at :2:59 and follow transcript2:59
So whenever a plant absorbs some carbon dioxide
from the air, it absorbs that amount of carbon-14,
and that carbon-14 will then make its way through the food
chain and end up in herbivorous animals, carnivorous
animals, us, anything made of wood, et cetera.
So we continually intake small amounts of carbon-14 from the
diet, and of course, we give out carbon-14 when we breathe,
which means it reaches a steady state.
So in a living organism, the amount of
carbon-14 is at a steady state during life,
but of course when you die, all this stops.
Play video starting at :3:47 and follow transcript3:47
But the decay of carbon-14 through radioactive processes doesn't stop.
So after death, the amount of carbon-14 drops with
radioactive decay at a very nice and fixed mathematical rate.
Play video starting at :4:2 and follow transcript4:02
So Willard Libby, who won the Nobel Prize
in 1960, developed this as a dating method
and he was able to calibrate it against historical objects,
so we can have a great deal of confidence in this method.
Play video starting at :4:17 and follow transcript4:17
The limitation on carbon-14 is that the object you're studying must be
more than a few centuries old, more than, say, 400 years old.
And the reason for that is very simple,
because if something is only 100 or 200 years old, the amount
of carbon-14 that is decayed is too small for us to measure accurately.
So if something is 500 years old, then we can get a good measurement; if
something is 10,000 years old, we can also get a good measurement.
Future archaeologists are going to have a problem,
and that is because the assumption of the carbon-14
in the atmosphere being constant has now broken down,
and this is due to testing of atomic bombs
in the atmosphere back in the 50s and the 60s.
Those atomic bomb explosions produced all sorts of isotopes including carbon-14.
And you can see on the graph here that prior to atom bomb
testing, the carbon-14 level was nice and steady, and then it jumps up
to a big spike because of atom bomb testing, and is slowly dropping
away, but it's going to take some time for it to get back to normal.
Play video starting at :5:34 and follow transcript5:34
What's this got to do with forensic science?
We're talking about things here that have been dead for centuries and centuries.
Well, let's look at the story of Peter Reyn-Bardt.
It was suspected that Peter Reyn-Bardt murdered his wife Malika back in 1960,
but there was no evidence.
More to the point, there was no body, her body was never
Play video starting at :6:1 and follow transcript6:01
found.
It was suspected that Reyn-Bardt had buried
her body in this place called Lindow Moss,
and this is a peat bog on the edge of Manchester.
Play video starting at :6:13 and follow transcript6:13
Now, peat is formed when the vegetation of the bog is compressed.
Play video starting at :6:20 and follow transcript6:20
And traditionally in Northern Europe, peat has
been used for centuries, particularly for fuel.
If the peat is dug out, it's cut up and
dug out and dried, it can then be burned as fuel.
Play video starting at :6:34 and follow transcript6:34
So, in 1983, a man was doing just that. He
was peat cutting when he found a skull fragment. An examination
of the skull fragment showed it still had tissue attached, even
brain tissue, which of course indicates it must be quite recent.
So this was handed to the police, the police went to Reyn-Bardt,
confronted him with the fact that they found this fragment, Reyn-Bardt
confessed and he was convicted of murder and sent to prison.
Play video starting at :7:6 and follow transcript7:06
Then someone had the idea of sending
that fragment to Oxford University for carbon-14 dating,
and when the results came back, it must have been quite a surprise
to Peter Reyn-Bardt because it turned out to be nearly 2,000 years old.
It wasn't from his wife after all.
Play video starting at :7:26 and follow transcript7:26
But what is surprising is that it's 2,000 years old, but it still contains tissue.
How can tissue survive that period of time?
And the answer comes in the very unusual chemistry of the peat bog.
Play video starting at :7:43 and follow transcript7:43
So on the left there is Lindow Moss. It's a peat bog, and as
I said, peat is formed by the compression of this vegetable matter in the swamp,
Play video starting at :7:53 and follow transcript7:53
and the vegetable matter, as it breaks down, releases chemicals into the water.
Most particularly, it releases tannins, and this is why
the water on peat bogs is often a brown colour.
It's the same chemicals that make tea brown,
and in fact they taste about the same too.
Play video starting at :8:14 and follow transcript8:14
So the peat bogs are acidic, and
also these tannins have antibacterial properties, and
that means that the microorganisms which are
responsible for the tissue breakdown can't grow.
Their growth is inhibited by these natural antibiotics, the tannins.
Play video starting at :8:35 and follow transcript8:35
Now, it's not true for all peat bogs.
On the left there you have Lindow Moss where
that skull fragment was found, on the right is Dartmoor.
Dartmoor should be well known to all of us because quite a few of the Sherlock
Holmes stories are set on Dartmoor, most famously "The Hound of the Baskervilles".
Play video starting at :8:57 and follow transcript8:57
The Dartmoor chemistry is quite different.
Dartmoor has 20,000 archaeological sites,
and that's one in the picture.
Play video starting at :9:7 and follow transcript9:07
Many of those archaeological sites are graves.
That one is a grave;
the depression in the centre of that stone circle is where the body was buried.
And yet, there's been almost no human remains found on Dartmoor.
The chemistry there is a little bit different,
the human remains dissolved away.
Play video starting at :9:30 and follow transcript9:30
Now, peat and peat bogs are not restricted to England, they're spread all
across Northern Europe, Northern Germany and especially Denmark.
Play video starting at :9:42 and follow transcript9:42
And as people have been cutting the peat for fuel
and for other reasons, they've been finding bodies in the bog.
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And these bodies, typically, are extremely well preserved
and they date back to about 2,000 years ago.
Play video starting at :9:57 and follow transcript9:57
And they are from the Celts,
the Celts were the people living in this part of Europe
at that time, and they, it is believed, practiced human sacrifice.
And what they would do is they would ritually kill
the person involved and then drop their body in the bog.
Play video starting at :10:15 and follow transcript10:15
What they didn't know is that body would be preserved for thousands of years.
Play video starting at :10:22 and follow transcript10:22
So, here's one of them.
Here's Grauballe Man, he was found in Denmark.
Play video starting at :10:28 and follow transcript10:28
And you can see remarkable preservation;
Play video starting at :10:32 and follow transcript10:32
that may be his original hair colour,
it's not his original skin colour,
that is a result of the tannins.
And typically, what used to happen when bodies such as
Grauballe Man were found by the peat cutters, they looked
so well preserved that the peat cutters would assume this
was a murder case, and they would call the local police.
The local police would come and they would take a look, and then
they would call the University and a
professor specializing in this would come over.
And in fact, in Denmark, they have a museum dedicated to these people.
Play video starting at :11:8 and follow transcript11:08
One bog person has been found in Lindow Moss, where Reyn-Bart is
believed to have buried the remains of his wife. This is Lindow Man,
and if you happen to be in London, you can
go to the British museum and take a look at him.
[BLANK_AUDIO]
Week 3A - 6 Ötzi Case; Summary
[MUSIC]
Well, let's end this lecture
by looking at the oldest body in the world, and this is Otzi, who
was found in the ice, high up in the Alps.
And he was found high up in the mountains by a pair of hikers.
And what had happened was that the warmer climate had caused a lot of snow and ice to
melt,
and his body had become partially exposed.
Play video starting at ::44 and follow transcript0:44
Well, when he was seen by these two hikers,
they of course assumed he was a recent accident victim
and they called the local authorities, and then of
course, it was realized he wasn't a recent accident victim.
He had actually been out there in the ice
for many, many years,
and it turns out that he had died up there in the mountains 5000 years ago.
Play video starting at :1:10 and follow transcript1:10
His body had been covered in snow, encased in
the ice, and had been preserved for 5000 years.
And many of his possessions such as the axe
he had with him, his clothes, were also preserved.
Play video starting at :1:27 and follow transcript1:27
We don't know why he was up in the
mountains, we do know that he was injured; there's an
arrowhead buried in one of his shoulders. But we also
know that he found a rather curious place to die.
Play video starting at :1:41 and follow transcript1:41
When these two hikers were hiking in the
mountains, they thought they were inside Austrian territory,
so when the body was found, it was taken to Innsbruck in Austria for further studies.
Play video starting at :1:54 and follow transcript1:54
It's only later that someone realized that he had actually crossed by a few metres
into what is now Italian territory to die,
Play video starting at :2:5 and follow transcript2:05
so the Austrians had to hand him over to the Italians,
and now he's in a museum of his own in Bolzano, Italy.
Play video starting at :2:13 and follow transcript2:13
So, Otzi is believed to be the oldest body in
the world, preserved by the ice and snow of the Alps.
Play video starting at :2:25 and follow transcript2:25
Well, in this lecture we have looked at many different techniques that can be
used to determine time of death, depending on how long the victim has been dead.
We looked at Rigor Mortis, Algor Mortis, and Livor Mortis,
which lasts for a day or so or two days.
We've taken a look at some of the circumstantial
evidence that can be used and will be increasingly used.
Play video starting at :2:49 and follow transcript2:49
For bodies that have been dead a bit longer, we can look
at the state of putrefaction, we can do some entomology with the maggots.
Play video starting at :2:57 and follow transcript2:57
And then getting into more historical archaeological territory,
we have FUN analysis, we have bone fluorescence,
we have carbon-14 dating.
But all the same, whichever technique we use
to determine time of death, we have to understand
that it can be effected by external environmental factors,
so all of these estimates are subject to errors
of one magnitude or another.
[BLANK_AUDIO]
Week 3B - 1 Blood
No transcript in English
Week 3B - 2 Tests for Blood
[MUSIC]
Well, if we have a stain on a suspect or
at a crime scene that we suspect might be blood,
how do we demonstrate that it is blood?
Play video starting at ::29 and follow transcript0:29
Well, there's a number of quite simple chemical tests
which we can use as presumptive tests for blood.
Play video starting at ::36 and follow transcript0:36
One of the old ones is called the Benzidine test.
This tends to be not used anymore because of the toxicity of the chemicals involved.
Play video starting at ::45 and follow transcript0:45
An excellent test that gives a nice
colour reaction is the Kastle-Meyer test using phenolphthalein,
and another very good reagent for testing for blood is Luminol.
All
Play video starting at :1: and follow transcript1:00
of these tests are based on the chemical property of blood, that it can catalyze
the break down of hydrogen peroxide to water and oxidizing species.
[BLANK_AUDIO]
Let's take a look at the Kastle-Meyer test.
What you need for doing the Kastle-Meyer test is reduced phenolphthalein.
Play video starting at :1:24 and follow transcript1:24
Now on the left, this is phenolphthalein in
its acidic form, which is a colourless material.
Play video starting at :1:34 and follow transcript1:34
But in alkali, phenolphthalein loses a proton and turns into
its alkali form, which is a very bright pink colour.
Play video starting at :1:45 and follow transcript1:45
Now if this alkaline form is reacted with zinc powder, it's reduced,
Play video starting at :1:52 and follow transcript1:52
and this reduced form is, once again, colourless.
Play video starting at :1:57 and follow transcript1:57
Now, in the presence of an oxidizing agent, that
reduced form is converted back into the bright pink form.
Play video starting at :2:5 and follow transcript2:05
So if we give it hydrogen peroxide, this is an oxidizing agent, but hydrogen
peroxide alone cannot turn the reduced form back into the pink alkali form.
What it needs is a catalyst and
one excellent catalyst for this reaction is blood.
Play video starting at :2:29 and follow transcript2:29
So if we have a suspected blood stain, we treat it with reduced phenolphthalein and
hydrogen peroxide, and we see the colour change to pink, then it probably is blood.
Play video starting at :2:45 and follow transcript2:45
But it is still only a presumptive test for blood,
it doesn't prove it's blood.
It just says, it's most likely to be blood.
This is because there are other materials,
not just blood, that can catalyze this reaction.
For instance, a potato, it turns out that there are
very powerful enzymes in potatoes which are excellent catalysts for this reaction.
So, potatoes are one example of something that can give
what we call a false positive in the Kastle-Meyer test.
There's a mysterious stain on this piece of tissue paper here.
Play video starting at :3:28 and follow transcript3:28
Could be a blood stain,
Play video starting at :3:30 and follow transcript3:30
but then, old blood stains just look like brown stains, so
it could also be paint or chocolate or something like that.
But what we are going to do is to use the
Kastle-Meyer test to find out if that is a blood stain.
Play video starting at :3:48 and follow transcript3:48
This is just a little bit of ethanol.
This is the Kastle-Meyer reagent from reducing
alkaline phenolphthalein with zinc,
and you can see a little bit of the zinc in the bottom of the vial.
[BLANK_AUDIO]
And you notice, when we
add the Kastle-Meyer
reagent, nothing happens.
That's because we haven't added the
oxidizing agent, which is hydrogen peroxide.
Play video starting at :4:45 and follow transcript4:45
And this isn't the dilute kind of hydrogen peroxide
that some people might use to bleach their hair.
This is 30% hydrogen peroxide, and this will burn holes in your epidermis.
Play video starting at :5:7 and follow transcript5:07
And you immediately see the pink colour, as
the hydrogen peroxide re-oxidizes the reduced form of phenolphthalein,
a reaction that is catalyzed by blood.
So probably, that brown stain on that tissue is blood.
Play video starting at :5:29 and follow transcript5:29
Well, the Kastle-Meyer test is not perfect because
a number of substances will also give positive results.
That is so-called "false positive" and one of
these substances that will do this is the humble potato.
Play video starting at :5:47 and follow transcript5:47
So, here is a potato.
I am going to treat it in exactly the same way.
[BLANK_AUDIO]
That was the ethanol.
This is the Kastle-Meyer reagent here.
[BLANK_AUDIO]
And finally, some hydrogen peroxide.
[BLANK_AUDIO]
Play video starting at :6:37 and follow transcript6:37
So, potato's a little bit slow until it goes pink.
[BLANK_AUDIO]
Week 3B - 3 Precipitin Technology
[MUSIC]
Play video starting at ::18 and follow transcript0:18
For if you've done your Kastle-Meyer test, or your Luminol Test, and you've
determined that a stain found at the crime scene really is blood, there is still
the question of whether it's human blood or whether it belongs to some animal.
Play video starting at ::33 and follow transcript0:33
And we can use antibody technology to determine which species blood comes from.
Play video starting at ::42 and follow transcript0:42
The way this is done is that a sample of human blood is injected into a rabbit.
The rabbit's immune system reacts to the presence of the human blood, and
it produces antibodies against those components in the human blood.
Play video starting at :1: and follow transcript1:00
So serum from that rabbit's blood can then be used as the test reagent.
Play video starting at :1:6 and follow transcript1:06
For instance, if we take our suspected human blood and
treat it with the rabbit serum,
Play video starting at :1:15 and follow transcript1:15
then when the human blood meets the rabbit serum that contains the antibodies,
then the antibodies of course will bind to components in the human blood, and
there will be a distinctive sign that there is an interaction.
If the two interact, then it proves that the sample is from human blood.
Play video starting at :1:37 and follow transcript1:37
This is usually done in a gel.
Play video starting at :1:40 and follow transcript1:40
So the antigen and the antibody are placed in separate wells in a gel,
and then using an electric field, they are induced to migrate towards each other.
Play video starting at :1:55 and follow transcript1:55
If there is an interaction between the antibody and the sample,
when the two meet, then there will be a visible precipitin line in the gel.
Play video starting at :2:5 and follow transcript2:05
If there's no interaction, then there is no visible line, and
you know that it's not human blood after all.
Play video starting at :2:14 and follow transcript2:14
This kind of technology is important.
It has been used.
For instance, some years ago, this man,
Christopher Nudds, was accused of killing his friend, Fred Moss.
Part of the evidence for this accusation was the presence of
many blood stains in Christopher Nudds' Range Rover.
But it turned out that Nudds was a hunter.
So the blood stains, presumably, were from some of the birds and
animals that he had captured and killed and driven back home in his Range Rover.
Play video starting at :2:51 and follow transcript2:51
So the precipitin test had to be used
to find out from which species all of these blood stains came from.
And sure enough, most of the blood stains in the Range Rover were from hunting.
They came from birds and animals such as rabbits.
Play video starting at :3:7 and follow transcript3:07
However, that was most of the blood stains, it wasn't all of the blood stains.
Play video starting at :3:13 and follow transcript3:13
Some of the blood stains indeed turned out to be human.
Play video starting at :3:19 and follow transcript3:19
Once the human blood stains have been identified,
then it was possible to use DNA to find out whose blood it was, and
it turned out that human blood in the Range Rover matched Fred Moss.
Play video starting at :3:34 and follow transcript3:34
Christopher Nudds was subsequently convicted of this murder,
and it's going to be a long time before he goes hunting again.
Week 3B - 4 Blood Spatter Analysis
[MUSIC]
So we've talked about blood biochemistry
and how we can use blood biochemistry to determine
where blood comes from, and who it belongs to.
Play video starting at ::30 and follow transcript0:30
So now let's talk about some blood physics and
see if we can work out how the blood got there.
So what we're going to do is take a look at some blood patterns,
and see if we can reconstruct the crime from the pattern of the blood.
Play video starting at ::46 and follow transcript0:46
So if there is blood on the suspect, from looking at how
the blood is distributed, can we understand how the crime was committed?
Play video starting at ::57 and follow transcript0:57
The technical term for this distribution of the blood on
the suspect in the crime scene is called blood spatter,
so what we're going to do is blood spatter analysis.
Play video starting at :1:10 and follow transcript1:10
So, here are some typical marks in blood that might be found at a crime scene.
Both of these marks come from the transfer of blood.
So in this case, blood has got on an object
and then has been transferred to the place where it's found.
So the one on the left, for instance, clearly someone has
stepped in blood, and this is a partial bloody foot print.
Play video starting at :1:37 and follow transcript1:37
The one on the right is a hand print in blood.
Someone has got blood on their hand, and their hand is
covered in blood, and then it's been smeared on the wall here.
Play video starting at :1:49 and follow transcript1:49
The pattern, the way that the blood is distributed, can tell
you about where the blood came from and how it got there.
So if in a violent crime an artery is severed,
Play video starting at :2:2 and follow transcript2:02
then there will be a very characteristic pattern of arterial spurting.
Play video starting at :2:8 and follow transcript2:08
So, because arteries come directly from the
heart, the pressure in the artery varies
as the heart beats, and this means that blood will spurt from the artery.
So instead of a continuous flow, you will get a spurt with each
heartbeat, and this gives a splash of blood, in this case, on the wall.
And because it's a relatively large amount of blood coming
from the artery, it will then dribble down the wall.
Play video starting at :2:34 and follow transcript2:34
This is called arterial spurting.
Play video starting at :2:39 and follow transcript2:39
On the other hand, if someone has a much smaller wound,
and for instance, is standing there wondering what to
do, then you will get a pattern of blood drips.
Play video starting at :2:50 and follow transcript2:50
Now, the exact pattern will depend on the surface in question,
and also how long the person stands there with blood dripping into the pool.
Play video starting at :3:2 and follow transcript3:02
The pattern created by flying blood will also depend on
the violence of the event that caused that blood to fly.
Play video starting at :3:12 and follow transcript3:12
If it's a relatively low energy event, for instance, an
ordinary fight, then you will get low velocity blood spatter.
Play video starting at :3:22 and follow transcript3:22
This can also be from blood that is falling
from a wound, and also blood that is cast off.
For instance, if someone is struck with a weapon and the assailant
then pulls the weapon back to take a second blow, as he
pulls the weapon back, there will be some blood drops cast off
from the weapon, and these would also give you low velocity blood spatter.
Play video starting at :3:49 and follow transcript3:49
Thinking about someone being attacked by a weapon,
for instance, being beaten with a baseball bat,
this is a relatively energetic event.
The blood that's flying around will move somewhat faster, and this
will give medium velocity spatter as shown in the picture here.
Play video starting at :4:6 and follow transcript4:06
The most energetic events would, for instance, be associated with gun shots,
and this gives high velocity blood spatter, where you have a lot
of small droplets of blood moving very fast, a little bit like a mist.
So this is high velocity blood spatter.
So by looking at these patterns of blood, the forensic
scientist can determine something about what happened in the crime.
Play video starting at :4:32 and follow transcript4:32
Now, let's consider a falling drop of blood.
A blood drop, as it falls, is roughly spherical.
Play video starting at :4:39 and follow transcript4:39
And if it hits the floor at an angle of
90 degrees, then you will get a circular blood spatter mark.
Play video starting at :4:51 and follow transcript4:51
But suppose that drop of blood doesn't hit the floor at 90 degrees,
suppose it hits the floor at an angle,
Play video starting at :4:59 and follow transcript4:59
then you will not get a circular pattern on the floor,
you'll get this elongated shape.
Play video starting at :5:7 and follow transcript5:07
And maybe, if the blood, as it hits the
floor, has enough energy, there will be a little splash.
So in front of the main elongated shape, there will be a
little extra dot of blood that bounced out from the main droplet.
Play video starting at :5:23 and follow transcript5:23
So for instance, you may have a pattern like this.
So here the blood has come from the left, because you can
see the main shape followed by a smaller droplet on the right.
Play video starting at :5:36 and follow transcript5:36
In fact, we can correlate the shape of these
blood droplets with the angle at which they hit the surface.
So when you have a 90 degree angle, we get this circular pattern,
Play video starting at :5:50 and follow transcript5:50
and as you go through to a very acute angle, it becomes more and more elongated.
So with a very acute angle of ten
degrees, you get this very long blood droplet shape.
[BLANK_AUDIO]
Now, suppose at the crime scene you
have multiple blood droplets in different places.
Play video starting at :6:13 and follow transcript6:13
We can work out which point in space was the origin
of those blood droplets by plotting lines backwards from the droplets.
Where all of the lines cross, which is called the point of convergence,
this would have been the source of the blood.
Play video starting at :6:32 and follow transcript6:32
Now when we look at a diagram like this in two dimensions,
it looks very simple, but of course, crimes occur in three dimensions.
So, we have to do this kind of blood spatter analysis in three dimensions.
Play video starting at :6:48 and follow transcript6:48
So if we can plot the lines back from the bloodstains, for instance, on the
wall to a point of convergence, then we
know in three dimensional space where the crime happened.
So in this example for instance,
Play video starting at :7:8 and follow transcript7:08
plotting the lines back from the blood stain pattern on the wall gives us the
height above the floor at which this event that generated the blood happened.
So if that height above the floor is say, five feet,
then we'd know the victim was still standing at the time.
If that height above the floor is only a few inches, then of course,
we know the victim was already on the floor when they were being beaten.
And this is very important evidence for reconstructing the crime scene.
Play video starting at :7:40 and follow transcript7:40
Now of course, these diagrams we're using here are very, very simplified.
And in a real situation, it would actually be
much more complicated to work out the point of convergence.
In fact, if you have a crime scene with
even more blood than this, it may just be impossible
because there's just too much blood at the
crime scene to be able to interpret the situation.
[BLANK_AUDIO]
Week 3B - 5 Lord Lucan Case;
Summary
[MUSIC]
Let's take a look at
the case of Lord Lucan.
This is actually a quite complicated case,
but we're going to look at some of the blood
evidence to try and work out what might have happened.
Play video starting at ::30 and follow transcript0:30
Now, Lord Lucan had been a banker, but he
changed his career and he'd become a professional gambler.
Play video starting at ::39 and follow transcript0:39
This turned out to be not such a good
career move, because he was quite deeply in debt.
Play video starting at ::45 and follow transcript0:45
This of course resulted in some marital troubles,
and he was separated from his wife, Lady Lucan.
Play video starting at ::53 and follow transcript0:53
Now, what do we actually know that happened?
Well, at about 9:45 pm on the evening of November the 7th,
1974, Lady Lucan ran into a pub near where she lived.
She was bloodstained, and she cried out, "Help me,
help me, help me, I've just escaped from being murdered."
Play video starting at :1:15 and follow transcript1:15
When police went to her home, they found that the children's nanny was dead.
Her body was in a sack, but
the children themselves were unharmed upstairs and asleep.
Play video starting at :1:29 and follow transcript1:29
So, what do we have at the crime scene?
Well, the house has four upper floors and there's a ground floor.
Nothing apparently happened in the upper floors.
Play video starting at :1:40 and follow transcript1:40
A bent, bloodstained lead pipe was found in the hallway, and there were bloodstains at
the top of the stairs. These stairs led down to a basement.
The door to the stairs and to the basement was open; in the breakfast
room downstairs in the basement, there was blood on the walls and the floor.
There was a pool of blood in which a man's footprint could be seen, and
it was down there that there was the bloodstained sack containing the nanny's body.
Play video starting at :2:13 and follow transcript2:13
Well, what do we know about Lord Lucan on this day?
Play video starting at :2:17 and follow transcript2:17
Well, what we know is at 11:30 that night, Lord
Lucan visited a friend who lived about 60 kilometres outside London.
Play video starting at :2:27 and follow transcript2:27
When he was there, he wrote and posted some letters, and then he left.
His car was found down by the seaside three days later.
Play video starting at :2:37 and follow transcript2:37
Since that visit to his friend, Lord Lucan has never been seen again.
Play video starting at :2:44 and follow transcript2:44
But from what he wrote in the letters, we do
have his version of the events on that fateful evening,
Play video starting at :2:53 and follow transcript2:53
and his story goes as follows.
He was walking past the house and he saw a struggle going on in the basement.
Play video starting at :3:2 and follow transcript3:02
Now in this kind of house, the basement has windows which
you can see from the street, so this is quite reasonable.
Play video starting at :3:10 and follow transcript3:10
So he went in because what he had seen, he
said, was that a man was attacking his wife, Lady Lucan.
So he went in to help Lady Lucan.
The man ran off but he was unable to follow the man,
to chase the man, because he'd slipped in the pool of blood.
Play video starting at :3:32 and follow transcript3:32
Then, after Lady Lucan ran out of the house to get help from down at the pub,
he had fled, he had run away, because he
thought that he would be blamed for this crime.
Play video starting at :3:46 and follow transcript3:46
Well, we do have a witness of course.
The witness is Lady Lucan.
So what is Lady Lucan's version of the story?
Play video starting at :3:54 and follow transcript3:54
Well, she says that at 8:30 that evening, the nanny had put the children to bed.
Play video starting at :4:1 and follow transcript4:01
This nanny, a lady called Sandra, happened to be about the same height and the same
weight as Lady Lucan, and normally, this day
would've been her night off, but she'd exchanged it.
Play video starting at :4:14 and follow transcript4:14
After putting the children to bed, the nanny had gone down the basement to make
some tea, but had seemed to take a very long time to make the tea.
So about 9:15, Lady Lucan had gone to look for her.
Play video starting at :4:29 and follow transcript4:29
She then says that she was attacked by her husband in the hallway,
and they fought, then when they stopped fighting, she was able to get away,
she escaped to the pub to get help.
Play video starting at :4:42 and follow transcript4:42
So who's telling the truth?
Play video starting at :4:45 and follow transcript4:45
Well, we have to look at the forensic evidence.
Play video starting at :4:49 and follow transcript4:49
So let's look at some of the forensic blood evidence.
Play video starting at :4:55 and follow transcript4:55
This is 1974, so it's long before all the DNA technology came along,
so we have to rely on blood type.
Play video starting at :5:3 and follow transcript5:03
Now, Lady Lucan was type A,
Play video starting at :5:7 and follow transcript5:07
the nanny was type B.
Play video starting at :5:11 and follow transcript5:11
So what about the blood stains around the house?
Play video starting at :5:14 and follow transcript5:14
What blood types were they?
Well, the blood at the top of the stairs was type A,
Play video starting at :5:20 and follow transcript5:20
the blood in the basement was type B, whereas the bloodstains on the lead pipe,
some of them were type A and some of them were type B.
Play video starting at :5:34 and follow transcript5:34
So, based on the blood evidence, where was Lady Lucan attacked?
Was it on the ground floor as she claimed,
or was it in the basement as Lord Lucan claimed?
Play video starting at :5:49 and follow transcript5:49
And from the evidence presented, did Lord Lucan slip in the blood,
or did he step in the blood?
Play video starting at :5:57 and follow transcript5:57
Well, as we know, Lord Lucan fled.
There have been no confirmed sightings of Lord Lucan since that night,
Play video starting at :6:5 and follow transcript6:05
therefore he was never arrested and never charged and there was never a trial,
and now, he is legally presumed to be dead.
Play video starting at :6:15 and follow transcript6:15
So in this lecture, we've looked at what is blood, what
is blood made of, and what components of blood are forensically useful.
Play video starting at :6:24 and follow transcript6:24
We've looked at the scientific basis of blood types,
how blood type can be used, even though it is not individualized.
Play video starting at :6:33 and follow transcript6:33
We have looked at some of the tests for blood, so
that we can determine whether a stain is blood or not.
And we've had a brief look at how we
can determine how the pattern of distribution of blood came about,
and how we can use blood spatter to reconstruct the crime.
[BLANK_AUDIO]