Shalti Serels
Forensics Final Review Sheet
History of Forensics, Evidence, Fingerprints & Blood:
- General Forensics:
o Forensic Science – “of the forum” Methods of science applied to public
matters
o Scientific Method:
 Observation – Collect Evidence
 Inductive Reasoning – Acquiring information
 Hypothesis
 Deductive Reasoning
 Theory
o Locard’s Principle: “Every contact leaves a trace”
- Evidence:
o Evidence – Anything that tends to establish or disprove facts.
o Testimonial Evidence – Consists of what is said in court by a “competent”
witness
 Expert Testimony – Scientific evidence presented by someone
who establishes credibility to the court.
 Frye Standard – Jury had the power to admit expert
scientific evidence
 Doubert ruling – Revised Fry Standard to be decided by
Judge
o Physical Evidence – Tangible items that tend to prove some material facts
o Value of Physical Evidence:
 Class – Material that can be associated with a general source
 Individual – Material that can be associated with a single source
o Types of Physical Evidence – Blood, glass, hair, fingerprints, drugs etc.
o Studies:
 Pathology – Disease
 Coroner – Dead Body
 Ballistics – Guns
 Spectroscopy – Chemical Fingerprints
 Dactylography – Fingerprints
 Entomology – Insects
 Odontology – Teeth
 Polygraphy – Lie detector
 Toxicology – Effects of chemicals
 Botany – Plants
 Serology – Bodily fluids
 Osteology – Bones
o People:
 Bertillon – 1879 Anthropometry = ID people by body
measurements [failed]
 Galton – 1892 Fingerprints
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 Locard – Forensics investigator in the early 1900’s. Locard’s
Principal
 Watson & Crick – 1959 Discovered DNA Double–Helix
Fingerprints:
o Visible Prints – Fingerprints left by a finger that had touched blood,
paint, etc.
o Plastic Prints – Fingerprint made as indentations in soft material
o Latent Prints – Fingerprints made by the deposit of perspiration or
body oils, invisible to the naked eye.
o Whorl – Basic fingerprint pattern
o Arch – Basic fingerprint pattern
o Loop – Basic fingerprint pattern
o Ulnar loop – Fingerprint loop towards the pinky finger.
o Ulna – Bone in forearm closer to the pinky
o Radial loop – Fingerprint loop towards the pinky finger.
o Radius – Bone in forearm closer to the pinky
o Minutiae – Small details of fingerprints, ridge characteristics
 Delta – Triangular area found in all loop and whorl patterns
 Core – Center of fingerprint
 Island
 Scar
 Short Ridges
 Dot
 Bifurcation
o Henry Classification – Equation to help separate fingerprints into
groups to help classify them, using the number and placement of
whorls
o Skin anatomy:
 Sweat gland – Gland in human skin that allows skin to sweat
 Chemical components of sweat: 99% Water; .5% Salt; .5%
Organic Compounds = Amino acids, Lipids, Oils % Vitamins.
 Epidermis – Top layer of skin, protects the Dermis
 Dermis – Lower layer of skin
 Dermal Papillae – Between the Epidermis and Dermis. This is
where fingerprints are formed.
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o Fingerprint Detection:
 Powder/Dusting – Good on hard non–absorbent surfaces, “lift”
resulting print with tape, very difficult technique to use
properly
 Iodine – Good on porous paper, reacts with fatty oils, print is
purple and temporary
 Cyanoacrylate ester [Superglue] – Good for non–porous
surfaces, print is white and permanent
 Ninhydrin – Reacts with amino acids, good on porous surfaces
like paper, print is orange–purple
 Silver Nitrate – Reacts with salt to form silver chloride, which
is then converted to dark silver oxide.
Blood:
o Presumptive Blood Test – Tests for the presence blood but it is not
confirmatory. A negative test, however, verifies the absence of blood.
o Kastle–Meyer Test – Reagent and hydrogen peroxidereacts with blood
stain and produce deep pink color. [Many substances can produce false
positives such as potatoes and horseradish]
o Hemastix – Turns blue when mixed with blood, as the Heme in
hemoglobin break down peroxides with the production of oxygen, the
oxygen reacts with the Benzidine product in the hematix test strip.
o Luminol – Very sensitive indicator for dried or washed blood. Quickly
spray on suspected bloodstain and makes old bloodstains glow.
[Certain Metals can cause false positives]
 Chemiluminescence – The emission of light from a chemical
reaction.
o Precipitin Test – Test that distinguishes between human and animal
blood.
o Antibodies – Proteins in the blood that tag, destroy or neutralize
harmful foreign substances, producing an immune response.
o Antigens – Foreign substance that produces an immune response
o Agglutination – A type of allergic reaction where red blood cells
clump together in response to a particular antibody
o Antiserum – human or animal serum containing antibodies that are
specific for one or more antigens.
o Plasma – The fluid part of Blood
o Metabolites – Organic molecules involved in the process of
metabolism
o Erythrocytes – Red Blood Cells
o Leukocytes – White Blood Cells
o Phenotype – Characteristic
o Genotype – Gene that produce characteristic
Phenotype [Blood Type]
A
B
AB
O
IA IA
IB IB
IA IB
ii
Genotype
IA i
IB i
o Rh factor – Another means to classify blood type. People who have it
are called RH+ and those without it are RH–
Determining Post Mortem Interval, Forensic Entomology & Forensic
Anthropology:
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Traumatic Death
o Cause of Death – The disease or injury that initiated the lethal chain of
events, however brief or prolonged, that led to the death.
o Mechanism of Death – A biochemical or physiologic abnormality
produced by the cause of death that is incompatible with life. The
actual science of how the person died.
o Manner of Death – Either: Natural, Accidental, Homicidal or Suicidal
o Algor Mortis:
 The body immediately begins to cool down after death
 Body temperature decreases by 0.75˚C an hour for the first 12
hours.
 After 12 hours, the cooling rate slows down to 0.4˚C. Until the
body reaches the ambient temperature [temperature of the
environment]
 Rate of cooling is affected by:
 Water: Cools faster
 Body Fat: Cools slower
 Clothing: Cools slower
 Air Temp: Cool faster on cold day than hot day.
o Rigor Mortis:
 Within 1–2 hours after death, the muscles begin to stiffen as
their storage of ATP depletes. Rigor Mortis refers to the
stiffening of the body.
 Stiffening begins in the face and jaw and moves downwards
until it reaches the feet. This process takes about 8–12 hours
 As the muscles begin to breakdown, they begin to relax in the
same order they became stiff. By 24–48 hours after death, the
body is completely relaxed.
o Livor Mortis:
 The settling of blood, resulting in a reddish or purplish color
pattern.
 Lividity [fixed after 10–15 hours after death] can indicate the
position the body was in after death.

-
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When lividity becomes fixed, the color pattern will not change
even if the body’s position is altered.
o Appearance of the Eyes:
 A thin film forms over the eyes within minutes after death as
the eyes dry out.
 The eyeballs become soft as pressure in the eyeball decreases.
 The eyes become cloudy as red blood cells are broken down
and release potassium. If the eyes are open the eyes become
cloudy after 3 hours, if eyes are closed process takes 24 hours.
 With an Ophthalmoscope, red blood cells in the veins of the
retina, which is the light–sensitive area in the back of the eye,
continue to move for several hours after death.
o Stomach Contents:
 Undigested stomach content – Death occurred 0–2 hours after
meal.
 Takes 4–6 hours for stomach to empty completely
 12 hours for food to leave small intestines
 Factors that affect digestion time:
 Fatty meal – slow down digestion
 Illness – Slows down digestion
 Fear – Speeds up
 Alcohol –
 Medication & Drugs –
Forensic Entomology:
o Can help estimate time of death, if body was moved, submerged in
water, the location on the body of before death injuries or how a body
was stored.
o Analysis of Entomological Evidence:
 Life Stage of insect
 Species Identification – Dichotomous Key
 Larval Analysis: length, mass, girth [thickness]
 Thermal History
Forensic Anthropology: A type of aaplied anthropology that specializes in the
changes and variations in the human skeleton.
o Osteons – Structures in bones that carry blood supply
o Function of bones:
 Support, Protection, Movement and Produce Red Blood Cell.
o Epiphyses – growth plates found at the end of long bones. Form in
childhood and fuse to the bone during early adulthood.
o Diaphysis – Shaft of long bone.
o Symphysis – Place where two bones meet and rub.
o Sutures – immovable joints where bones are joined together. They are
visible as seams on the surface. [Especially on skull]
o Caucasoid – People pf European, Middle Eastern and East–Indian
descent
o Negroid – People of African, Aborigine and Melanesian descent
o Mongoloid – People of Asian, Native American and Polynesian
descent
o Tendons – Connect bones to muscle
o Ligaments – Connect two bones
o Long Bones – Are longer than they are wide; bones in the arms, legs,
hands and feet. [can be used to determine approximate height of
person]
o Short bones – Are as long as they are wide; bones in wrist and ankle
o Flat bones – Are flat and enclose soft organs; dkull, scapula, sternum,
hip bone and ribs.
o Irregular bones – Are irregular shpaed; vertebrae and some bones in
the skull.
o Pelvis – can help deferentiate between remains of males and females.
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DNA
o DNA – Deoxyribonucleic acid, genetic material
 Polymer – made up of many subunits [made up of many
monomers]
 Double Helix – Made up of Sugar–Phosphate backbone and
Nucleotides.

o
o
o
o
o
o
o
o
o
o
o
o
-
The Backbone is made up of deoxyribose [5 carbon
sugar] and a phosphate group [negatively charged]
 Nucleotides/Nitrogenous Base – joined together make
up the units of DNA, base pairs.
o Guanine paired with Cytosine
o Adenine paired with Thymine
Gene – A specific sequence of nucleotides in the DNA
Chromosome – A long threadlike group of genes
Allele – A site where 2 genes that influence a particular trait are found
on a chromosome pair.
Protein – Fundamental components of all living cells [enzymes,
hormones, antibodies etc.] Made up of Amino Acids linked together.
 Hemoglobin and insulin are Proteins
 Amino Acid – An organic compound containing an amino
group and a carboxylic acid.
 Enzyme – A protein that causes a chemical reaction to occur.
DNA Polymerase – Enzyme whose function is to make more copies of
DNA
Primer – Strand of nucleic acids that act as starting point of DNA
synthesis. Needed for PCR
Polymerase Chain Reaction [PCR] – scientific technique to make more
copies of a given DNA molecule.
 Taq Polymerase – The enzyme normally used for PCR
Restriction Endonuclease – Enzyme that cuts SNA at precise points
producing a collection of DNA fragments of different lengths.
Restriction Fragment Length Polymorphism [RFLP]
Gel Electrophoresis – A procedure that separated DNA according to
size [look up how to use it because im not gonna write out all the
steps]
 Aggrose – Sugar used in Gel Electrophoresis
Probe – A portion of a DNA molecule with a known sequence of bases
that is used to find its complementary strand
Mitochandria – Organelle in most eukaryotic cells produces energy
[ATP] by Cellular Respiration.
 Mitochondrial DNA – Passed on solely by the mother as only
the Nucleus of the sperm cell fertilized and penetrated the egg
cell
P.S. Remember Vivian Vance and Tennessee