Exam 1 Flashcards
What is forensic science?
the application of science to those criminal and civil laws that are enforced by police agencies in a criminal justice system
Also called criminalistics
sir arthur conan doyle
Popularized physical detection methods in a crime scene
Developed the character Sherlock
mathiew orfila
father of forensic toxicology
Calvin Goddard
1891-1966
Used a comparison microscope to determine if a bullet was fired from a specific gun
Published study of tool marks on bullets
edmond locard
1877-1966
Locard’s exchange principle states that once contact is made between two surfaces or people, a transfer of material(s) will occur
Study of the material can determine the nature and duration of the transfer
Hoover
In 1932, he established a national forensics library to support law enforcement in the US
Oldest american forensics laboratory
In LA, created in 1923
stages of death in order
rigor mortis
livor mortis
algor mortis
rigor mortis
immediately following death, the muscles relax and then become rigid, shortening of the muscles
livor mortis
when the human heart stops pumping. The skin will appear dark blue or purple in these lower areas close to the ground
algor mortis
the process in which the body temperature continually cools after death until it reaches room temperature, enabling the medical examiner to establish the general time of death
forensic entomology
The study of insects and their developmental stages
Can help to determine the time of death by knowing when those stages normally appear in the insect’s life cycle
Determines a person’s time and place of death
what is a crime scene
A location where a crime took place
what is evidence
Anything presented in support of an assertion
search methods
spiral
grid
strip/line
quad/zone
direct evidence
Direct evidence is evidence that directly proves a fact, such as a witness’s testimony or a physical object.
Firsthand observation (eyewitness accounts, police dashboard video cameras).
Physical objects: A physical object retrieved from a location, such as a living person or a dead body
circumstancial evidence
also called indirect
Evidence that does not, on its face, prove a fact in issue but gives rise to a logical inference that the fact exists
For instance, a suspect in a crime was seen by a witness fleeing the scene on foot after a convenience store robbery
Doesn’t actually prove that this person did the crime
physical indirect evidence
Examples of physical evidence include guns, weapons, bodily fluids, a bloody knife or shirt, fired bullets
why is physical indirect evidence good
Physical evidence is more reliable than testimonial evidence because it can be tested scientifically and does not lie.
Can actually see and photograph it
Can prove that a crime has been committed
Can corroborate or refute testimony
Can question if witness actually saw it but can’t question if the gun was there
Can establish identity of persons associated with crime
Can allow reconstruction of events of the crime
biological indirect evidence
Biological evidence is bodily fluids and tissues that can be used to identify individuals and link them to a crime scene. This evidence can include:
Blood, Semen, Saliva, Skin, Hair, urine, bite mark, plant, pollen
Collected with cotton-tip applicators, clean forceps, and packaged
Not always visible to naked eye
class evidence
indirect
A type of physical evidence that is common to a group of people or objects, and can be used to place an individual into a general category such as blood type or gun caliber
individual evidence
indirect evidence
evidence that can be linked to a single source, and is considered the best evidence.
Includes tear patterns that match together
examples of individual evidence
Fingerprints
Handwriting
Tear patterns that can be matched together
Hair with a ROOT
Broken glass
DNA patterns
Physical matches like broken pieces of glass that fit each other perfectly
Striations on a bullet
7 S’s of crime scene investigation
secure the scene
separate witnesses
scan the scene
seeing the scene
sketch form
search pattern
secure collected evidence
Functions of hair
Protection
Brows and lashes protect eyes from sweat, dirt, and dust. Nose hair protects nose from germs and foreign objects so we sneeze it out. Skin is protected from sun, dust, and other small particles
Thermoregulation
Hair stands up and keeps heat close to body. Serves as insulation and protects against friction
Sense organ only found in mammals
how many hairs shed daily
- 100 from head
2 main types of body hair
shorter and thinner “vellus” hairs (peach fuzz) found on the body
The longer and thicker “terminal” hairs. Examples of terminal hairs include the hair on your head, facial hair, eyelashes, eyebrows, pubic hair, chest hair and belly hair
in what ways can hair vary
shape, color, length, texture, and diameter
arrector pili
tiny muscle surrounding hairs which make them stand up
sebaceous glands
secrete lubricating oil for skin and hair, also secretes sebum and slows down bacterial growth on skin
Morphology of hair
Shaft (cuticle, cortex, and medulla)
cuticle of hair
outside layer, transparent, has protective scales
Coronal, spinous, or imbricate
Scales always point to tip of hair
cortex of hair
middle layer where you find melanin
The cortex is the main body of the hair shaft.
The color, shape, and distribution of pigment granules (melanin)
Provides forensic scientist with points of comparison between individuals
medulla
core, most important part to forensic scientist, may be absent
The medullary index measures the diameter of the medulla relative to the diameter of the hair shaft
Usually less than ⅓ in humans, ½ or greater in animals
May be continuous, interrupted, fragmented, or absent
coronal scales
crown like, fine diameter, not usually in humans, seen in small rodents and bats
spinous scales
petal-like which are usually triangular shaped. Protrude from the hair shaft. Seen in seals and cats, not humans
imbricate scales
commonly found in humans, resemble puzzle pieces, overlapping scales
medulla in race (African, European, Asian)
African: fragmented or none
Euro: fragmented or none
Asian: continuous
Lanugo
A coat of delicate hairs found on human fetuses preterm
vellus hair
fine hair present on the body after birth and before puberty
terminal hair
larger, coarser hair of the adult
3 stages of hair growth
anagen
catagen
telogen
anagen
follicle actively producing hair and hair will grow
catagen
transition phase from anagen to telophase, not actively growing
telogen
when the follicle is dormant or resting. Hair routinely falls from skin. Most common type of hair found in crime scenes
Detecting DNA in hair roots is most likely in what stage
Anagen
How do fibers differ from each other
Chemical properties
Cross-sectional shape
Surface contour
Color
Length
Diameter
types of fibers
animal (protein)
plant (cellulose)
mineral
natural fibers
oldest fibers known to us
These are made up of cells
cashmere furs, cotton, silk
Any fiber that exists as a fiber in its natural state
Made of cells which can absorb moisture which makes them very comfortable
plant fibers
Seeds
Stems
Leaves
The most common plant fibers encountered in case work are cotton, flax (linen), jute, hemp
mineral fibers
Asbestos– a natural fiber that has been used in fire-resistant substances
Animal fibers
Hair–wool is most common, can be brushed, clipped, shed, usually from sheep
Fur–skin of animal is treated to be flexible and retains the fur, rabbit, mink, and fox
Webbing–don’t shed as easily as hair fibers, silk comes from cocoon of caterpillar, fibers are long
Scale protrusion!!
wool
commonly from sheep and most commonly used animal fiber
Finer woolen fibers used in clothes, coarse used in carpets
look at degree of scale protrusion and diameter
Silk
insect fiber that is spun by a silkworm to make its cocoon
Take cocoon, treat it, makes silk
Fibers are very long
synthetic fibers
produced solely from synthetic chemicals and include nylons (made by dupont, 2nd most common synthetic, polyesters (most popular synthetic fiber), acrylics, spandex, acetate, rayon
What makes fabrics unique
Color, size, shape, microscopic appearance, chemical composition, and dye content
Very unlikely for two people to wear the same fabric
Physical characteristics of fiber are examined by
Calculating density of fiber
Oxidation test (burn the fiber to evaluate ash, behavior of flame, and smells)
chemical characteristics testing of man made fiber
Burning tests—look at ash, odor, color of flame, reaction, size of flame
pH Testing
Evaluating any residues or component parts within synthetic fibers
Chemical Decomposition tests—treat the fiber with strong acids and bases and see how it breaks down
chromatography
separates the dye for analysis, accepted in court
pollen is most commonly found where
cuff of suspect’s pants
forensic botany questions
Who was with victim or at the crime scene/near time of death
What did the victim eat before dying
When was the crime committed/when was a specific person/vehicle/article at the scene
How long since it been sine postmortem interval/how long was body buried
when did botany become part of FBI training
1993 at national academy at Quantico, virginia
first mention of forensic botany
Plato’s Phaedo of 399 B.C
Describes sorates’ self administered death sentence of poison hemlock
What happened that made forensic botany legally acceptable
Trial of Richard Hauptmann who kidnapped and murdered the son of charles lindbergh
assemblages
groups of plants usually dominated by one species
assemblages require?
same:
Soil Type
Wind
Altitude
Moisture
Sunlight
Longitude and latitude
gastric contents and forensic botany
Cellulose can’t be digested!
If you open up stomach if victim died recently, cellulose hasn’t broken down (in corn and paper)
If these plants/cellulose are in last meal, we can estimate PMIs based on degree of digestion
pollen vs spores
The male reproductive structure of a seed plant is called a pollen grain, and is as small as a pinpoint.
A spore is the reproductive structure of fungi.
both have jagged edges so it attaches easily
can survive for decades
Both studied under a microscope and have resistant cell walls
cellulose
plant wall
forensic palynology
the study of pollen and powdered minerals (and spores)
how is the plant kingdom classified
seed and non seed
earliest plants like ferns and mosses were non-seed, produced by dispersing spores
seed plants
Predominant land plants, most likely to leave evidence at a crime scene
gymnosperms and angiosperms
Produce cones or flowers
gymnosperms
oldest seed plants
conifers
pollination (males produce seeds/pollen, wind brings it to female cone)
no fruits
includes pines and evergreens
conifers
largest, most familiar gymnosperm
angiosperms
corn, oaks, maples, and the grasses
have flowers
produce seeds in a fruit
very diverse and seen in almost every habitat, and therefore at almost every crime scene
pistil and stamen of flower
pistil is female and produces eggs
stigma is sticky, pollen lands here
style is a tube which leads to ovary
stamen is male and responsible for pollen production
filament is long stalk, elevates the anther that produces pollen
when pollination occurs, goes to stigma, sticks there, goes down the style and into ovary, fertilizing the plant. Ovary develops into a fruit
petal attracts pollinators
sepal is leafy part under petals
cross pollination vs self pollination
cross: 2 distinct plants
self: pollen to stigma within same flower
Endospores
Several types of bacteria that make endospores can cause diseases
Anthrax and botulism
pollen and spores as evidence
Larger pollen grains such as that of corn cannot travel far and can only drift with the wind about a ½ mile
Size, shape, surface texture, thickness of wall
Someone with cornflower or corn pollen was probably near a corn field
Fingerprints also known as
Dactylography/oscopy
Dactyloscopy
Study of fingerprints for id purposes
1880s fingerprints
Sir francis galton and sir E.R. henry developed the classification system for fingerprints that we use today (Galton-Henry method)
1999 fingerprint history
FBI developed the automated fingerprint id system (AFIS)
provides automated fingerprint searches, storage of photo files, and exchange of fingerprints and test results
Not only for criminals, employment, licenses, and social service programs
How many ppl in the country have their fingerprints recorded on AFIS
1 in 6 ppl
Fingerprint analysis in 1995 vs today
1995: 1 in 5 exams make a false ID
Today: reviewed by 2 examiners. 98.6% for one finger and 99.6% on two
Friction ridges
Small ridges that are raised portions of the skin, arranged in connected units
Formed at 10 weeks in utero (3 inches long)
Changing fingerprints
Stays the same forever unless permanent scars or skin disease
What layer affects fingerprints
Basal layer, grows faster than others
Sweat glands alternative names
Aporcine and eccerine
Apocrine glands
Associated w hair follicles
Eccrine glands
Found on ridges of hands and feet
Arches, whorls, and loops
Arch: Can be plain or tented gentle slopes
Loops: Radial (thumb) or ulnar (pinky). Most common type
Whorls: most complex, circular patterns
Core vs delta
Core: center of loop or whorl
Delta: triangular region
Minutiae
Points where print ridges come together or end, considered to be the uniqueness of an individual
Primary basis for fingerprint ID
How many common minutiae can people have
No more than 8
How to match fingerprints
12 match guideline
Patent fingerprints
Visible prints
Left on a smooth surface when liquids come in contact with the hand and then transferred onto surface
Clearly recognizable and needs no processing
Latent fingerprints
Caused by transfer of oils and other body secretions onto a surface
Not seen easily
Requires additional processing to be rendered suitable for comparison
Processing is also called development or enhancement
Dusting is most common
Ninhydrin
Chemical that bonds with amino acids in fingerprints
Produces blue or purple color
Used to lift prints from surfaces such as paper or cardboard
takes 1-2h to develop (heat and humidity make it faster) and lasts 24-48h
Used since 1910
Cyanoacrylate fuming method
Often called super glue method
Procedure to develop latent fingerprints
Super glue is heated to produce a fume and yields an off white colored print
use of heat and humidity speeds process
Worked on interior of car
Silver nitrate
Reacts to salt deposits in sweat
Once prints develop, should be photographed and removed from light source
Iodine fuming
Not permanent
Dirty brown colored print and needs to be photographed quickly bc it fades
Plastic prints
Impression left in soft material
Also called impression or indentation print
