Forensic Entomology

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Bellringer
• What do you think entomology is?
Objective
• Learn what entomology is and
what the three types of
entomology are.
Forensic Entomology
Entomology
• What is entomology?
• Entomology is the scientific study of
insects!!!
• EWWWW GROSS!!!!
Background check
• People come from all different backgrounds, so
let’s see who knows what about insects.
• On page 370 of the textbook take the quiz and test
your knowledge of the insect world. (1-14)
• Record your answers in your notes and in
complete sentences so you can refer back later.
Taxonomy
• Taxonomy is the classification of things in
an orderly way that indicates natural
relationships.
• This is how we sort different living
creatures.
Steps of Taxonomy
• Largest (most
general) category is
Kingdom. The
smallest (most
specific) category is
Species.
Example
What does this have to do with
forensics?
• Forensic Entomology is the use of insects and
other arthropods to aid in legal investigations.
• Arthropods are animals characterized by jointed
legs, a segmented body, and a hard, nonliving
exoskeleton.
Bellringer
• What are the three areas of entomology that forensic
scientists are concerned with?
Objective
• Know the three processes of death
The 3 general areas of forensic
entomology
• Urban entomology
• Insect damage to structures
• Stored products entomology
• Insects infesting foodstuffs
• Medicolegal entomology
• Insects that inhabit human remains
Forensic Entomology
• Forensic scientists are mostly concerned with
medicolegal entomology.
• They commonly use it to the determine postmortem
interval associated with the time of death.
• Postmortem Interval is the time elapsed since a person
has died.
Check point
• What is forensic entomology?
• What are the three types of entomology?
First
• Before we can study how insects
take over a person’s body once
they are dead we must learn and
understand the processes that
happen after a person dies.
The process of Death
• First off, death is a process and not an event.
• Cause of death is not the process of death.
• Different tissues and organisms in a living body
die at different rates.
Determining the time of death
• Most accurate if the body is found within the first 24 hours.
• Use the three indicators
• Algor mortis
• Livor mortis
• Rigor mortis
• After these time periods have passed other methods must
be used instead.
• Estimations based on the environment and the scene.
Algor mortis
• Algor mortis refers to the cooling rate of the
body after death.
• Immediately upon death, the body can no longer
metabolically maintain its temperature of 98.6
degrees Fahrenheit and begins to equalize its
temperature to that of its environment.
• Measuring the internal body temperature can
give you some indication of the time of death.
Newton’s Law of cooling
• Newton was one of the best physicist ever.
• Wrote an equation to predict the rate of
change in the temperature of a body using
the starting body temp and the air temp.
Glaister Equation
• Newton’s method doesn’t work well for dead
bodies.
• The Glaister Equation is used from 1 to 36 hours
after death, but is most accurate within the first
12 hours.
• ๐ป๐‘œ๐‘ข๐‘Ÿ๐‘  ๐‘ ๐‘–๐‘›๐‘๐‘’ ๐‘‘๐‘’๐‘Ž๐‘กโ„Ž =
98.4โ„‰−๐‘–๐‘›๐‘ก๐‘’๐‘Ÿ๐‘›๐‘Ž๐‘™ ๐‘๐‘œ๐‘‘๐‘ฆ ๐‘ก๐‘’๐‘š๐‘๐‘’๐‘Ÿ๐‘Ž๐‘ก๐‘ข๐‘Ÿ๐‘’
1.5
Glaister Equation
• Generally a body cools about 1 to 1.5 degrees Fahrenheit
per hour until it reaches ambient temperature.
• The temperature of the environment, type of clothing on
the body, wetness of the clothing, air movement, # of
layers of clothing, and other conditions must be taken
into consideration.
• Also, the greater the ratio of surface area to mass, as
with children or smaller adults, the faster the body cools.
Livor mortis
• Livor mortis refers to the pooling of blood in
the body due to gravity after the heart stops.
• It appears on the skin as a purplish-red
discoloration (like a bruise) and can give an
indication of the position of the body at the
time of death.
Livor mortis
• It begins within a half hour after death and is
most evident within the first 12 hours
• After 12 hours the discoloration will not move
regardless of how the body is repositioned
• This fact is useful when determining whether a
body has been moved after death
Rigor mortis
• Rigor mortis is a stiffness in the muscles
that occurs shortly after death.
• Immediately upon death muscles begin to
relax, but then some enzymes in your
muscles begin to act and cause your
muscles to become more rigid.
Rigor mortis
• Rigor mortis begins in the smaller muscles so it’s
first observed in the face, neck and jaw.
• The noticeable stiffness of rigor mortis can occur
within a few hours after death and is gone within
approximately 30 hours, leaving the body limp.
Rigor mortis
• Rigor mortis begins to disappear in the same
order in which it began.
• Rigor mortis is affected by the environmental
conditions such as temperature, dehydration,
condition of muscles, and their use prior to
death
• There are uncertainties in determining the
time of death from rigor mortis
Estimating Time of Death
Temperature of Body Stiffness of Body
Time Since Death
Warm
Not stiff
Warm
Stiff
Cold
Stiff
Cold
Not stiff
Not dead more than
3 hours
Dead between 3 and
8 hours
Dead between 8 and
36 hours
Dead for more than
36 hours
Checkpoint
• What are algor mortis, livor mortis,
and rigor mortis?
Reading Activity
• Read pages 380 and 381 and then answer the following
questions
1. What is autolysis and when is it first observed?
2. What is putrefaction and why is it so smelly?
3. What is mummification and why doesn’t it happen to every
dead body?
4. What is digenesis?
5. What variables have the largest effect on the rate of
decomposition?
6. How long would it take a body to become a skeleton if it was
out in 45 degree Celsius weather?
Case Study
• Is it possible to stop a body from
decomposing at all?
• Read the case study on pages 381 to 382.
“Colonel William Shy”
• How was this possible?
Tomorrow
• Life cycle of Insects and the Insects of Death
Bellringer
•What is algor mortis and
how is it different from livor
mortis?
Objective
• Finish learning about the process of
death
• Learn how the life cycle of insects is
used by forensic scientists to
determine the time of death of a
dead body.
How’d we learn this?
• Texas Body Farm: Caution…this is super gross!!
• https://www.youtube.com/watch?v=OFJrow7yaec
• What are the four steps of death in the video?
Reading Activity
• Read pages 380 and 381 and then answer the following
questions
1. What is autolysis and when is it first observed?
2. What is putrefaction and why is it so smelly?
3. What is mummification and why doesn’t it happen to every
dead body?
4. What is diagenesis?
5. What variables have the largest effect on the rate of
decomposition?
6. How long would it take a body to become a skeleton if it was
out in 45 degree Celsius weather?
Decomposing Whale
• Remember the process of death is not one step.
• As a formerly living thing decomposes gasses are released
inside the body which can create very large amounts of
pressure.
• Warning this video is disgusting…like really really gross…
• https://www.youtube.com/watch?v=d2CfYOJ5oxk
Objective
• Use the life cycle of insects to solve crimes
Life Cycle of Insects
• Knowing the life cycle of insects can help
forensic scientists determine how long they
have been infesting a body.
1.
2.
3.
4.
Egg – 12 hours
Larva (maggot) – 4 days
Pupa (Dark hard shell) – 3 days
Winged Adult (Flies) – 12-24 hours
Life Cycle of Insects
• Two bodies are found in the same area.
Which body has been dead longer?
A. One that is found with flies on it but no
signs of anything else.
B. One that is found with flies on it and
with empty pupae.
Insects of Death Reading
• Read pages 384 to 385, and then answer these questions.
1. What are the two most common insects found on corpses?
2. How many species of flies live on Earth?
3. In what order do flies arrive at a dead body?
4. Where do flies lay their eggs on a body?
5. Once fly eggs hatch what do they eat?
6. How do maggots raise the dead body’s temperature?
7. Where does most of the body's mass go?
8. Who takes over once the body dries out?
9. What percent of the original body weight is left behind by the end
of the decay stage of decomposition by the insects?
Body In The Basement
• Read all of page 386 and then answer the
following questions:
1. Why were specimens collected at the scene
raised in the laboratory?
2. Why was data on climatic conditions gathered?
Bellringer – Start New
1. What is algor, livor, and rigor mortis?
2. Fill in the chart: Temperature of Stiffness of
Body
Body
Warm
Time Since
Death
Not dead more
Dead between
Cold
Stiff
Dead between
Not stiff
Dead for more
3. What can you infer from find fly eggs on a dead body, but
not finding hatched eggs.
About 12 hours dead*
Temperature of Body Stiffness of Body
Time Since Death
Warm
Not stiff
Warm
Stiff
Cold
Stiff
Cold
Not stiff
Not dead more than
3 hours
Dead between 3 and
8 hours
Dead between 8 and
36 hours
Dead for more than
36 hours
Objective
• Answer questions to entomology video
Quiz on Friday
Scripts
Preserving Body Parts!
• Parts without muscles such as fingers can be preserved for
many hours, while major muscle containing parts such as arms
need to be re-attached and revascularized within 6-8 hours to
have a viable limb.
• Parts should be wrapped with moistened gauze and placed
inside a clean or sterile bag floating in ice water.
Forensic Entomology Video
1. After how many hours is entomology usually the best option
to estimate the time of death of a body?
2. A sampling of which insects, and in what stages, should be
taken back to the lab?
3. Why do forensic scientists preserve half of the larva they
take back to the lab and keep half alive?
4. What other information does an entomologist need to know
about the death site?
5. What two things do forensic scientists use to figure out the
exact temperature of the crime scene for the time the body
was there?
Forensic Entomology
• Part One:
• https://www.youtube.com/watch?v=VeOt
ScDxq6s
• Part Two:
• https://www.youtube.com/watch?v=Ov1t
UK8r6sM
Bellringer
• What is algor mortis and how does it help forensic scientists
determine the time of death?
Objective
• Be prepared for the quiz on Friday
Quiz on Friday
Answers
1. 72 hours
2. All insects found and in all stages
3. Preserve half so they know what it looked like
when it was picked up (evidence). Keep half living
so they can calculate how old it is and what
specific species it is
4. Temperature, environment, clothing, etc.
5. Local weather information and temperature data
collected at the sight for a couple of weeks after
the body is found.
Scripts
Fingers
• Fingers do not
contain muscles (other than
arrector pili). The muscles that
move the finger joints are in the
palm and forearm. The long
tendons that deliver motion from
the forearm muscles may be
observed to move under the skin
at the wrist and on the back of
the hand.
Other Uses of Insects
• Maggots love wounds, so maggots can help point
them out!
• Insects can help place a suspect at the scene of a
crime.
• The suspect has a bite from a bug that is only from
a certain area, but the suspect denies being there.
• Contraband trafficking can sometimes be traced by
identifying trapped insects that were not intended
to be shipped.
Other Uses of Insects
• The species of insects plastered on an automobile
radiator allowed investigators to refute a suspect’s alibi.
• The presence of drugs in a body can sometimes be
detected by harvesting and testing the feeding maggots.
• In civil cases, insects found in stored food products or
clothing can cause considerable discomfort as well as
monetary loses.
• Insects can also damage buildings
• Termites and carpenter ants
Case Studies
• Read the case studies on page 402-403, then
answer the following question:
1. How reliable can insects really be when
determining the time of death of a body?
Why should or shouldn’t it be used to
convict someone of murder? Give three
scientifically sound arguments to back up
your opinion.
Review Sheet
Bellringer
• What are two uses of insects found at
a crime scene that do not have to do
with estimating the time of death of
the victim?
Objectives
• Prove you know the ins and outs of
entomology.
POP Test!!!
• You may use your notes.
• If I even think you’re cheating this
time I will take your whole test and
throw it out…that means you get a
zero.
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