Forensics Winter Exam Content Flashcards
property of physical evidence that connects an individual or thing to a group that share similar characteristics
class evidence
property of physical evidence, narrows to one individual
individual evidence
examples of class evidence? (3)
- shoe prints
- blood type
- hair (w/o the follicle)
examples of individual evidence? (3)
- DNA
- hair (w/ the follicle)
- fingerprints
the initial location
primary crime scene
secondary location
secondary crime scene
evidence used to imply a fact but not prove it directly
circumstantial indirect evidence
material that comes from a proven or known source
control sample
very small pieces of evidence
trace evidence
evidence that (if true) proves an alleged fact, such as an eyewitness account of a crime
direct evidence
What are most wrongful convictions the result of?
faulty eyewitness testimony
when a person comes into contact with an object (or another person) across transfer of physical evidence can occur
Locard’s exchange principle
Why is it important to separate witnesses at the crime scene?
reduce the likelihood of them reporting into things they have not directly observed
the unbroken paper trail that follows evidence from the crime scene, through analysis, and all the way to the court room
Chain of Custody
5 components of a crime scene sketch?
- direction
- measurements
- evidence
- markers
- correct object placement
What type of evidence has allowed the Innocence Project to free individuals from prison for wrongful convictions?
DNA evidence
objects found at the scene of a crime
physical evidence
materials or substances of bodily fluids and tissues; evidence from an organic source human, plant, or animal
biological evidence
What are the most 2 important factors of securing a crime scene?
- make sure everyone is safe
- preserve and protect the area as much as possible
red blood cells
erythrocytes
platelets
thrombocytes
white blood cells
leukocytes
substances on cells that trigger an immune response
antigens
proteins that attach to red blood cells as an immune response
antibodies
most abundant cells in our blood; produced in the bone marrow and contain a protein called hemoglobin that carries oxygen to our cells
red blood cells (erythrocytes)
clotting factors that are carried in plasma; they clot together in a process called coagulation to seal a wound and prevent a loss of blood
platelets (thrombocytes)
they are part of the immune system and destroy infectious agents called pathogens
white blood cells (leukocytes)
clumping of red blood cells
agglutination
Universal donor?
O-
Universal recipient?
AB+
When a blood drop falls at a 90 degree angle, what shape of blood droplet will be produced?
circular blood droplet
used to find area of convergence
string method
What is the forensic value in blood typing?
can show the possible math of two samples
What type of evidence is blood typing?
class evidence
What type of evidence is DNA?
individual evidence
Size of blood droplet at 5 ft?
4 to 6 mm
Size of blood droplet at 25 ft?
1 to 4 mm
Size of blood droplet at 100 ft?
less than 1 mm
the … the height the … the drop
lower; smaller
What type of DNA can be individualized to a single person?
nuclear DNA
DNA from the nucleus of the cell individualized to a single person
nuclear
DNA from the mitochondria, passed down from the mother
mitochondrial
What part of the blood determines a person’s blood type?
presence or no presence of antigens A and B
DNA fingerprinting method
gel electrophoresis
Combined DNA Index System (DNA database)
CODIS
3 types of fingerprints?
- whorl
- loop
- arch
Percentage of loops in the world?
65%
Percentage of whorls in the world?
30%
Percentage of arches in the world?
5%
Most common finger print?
loops
How many deltas are in a loop?
1
How many deltas are in a whorl?
atleast 1 sometimes 2
What part of a fingerprint is class evidence?
ridge
What part of a fingerprint is individual evidence?
minutiae
What part of the finger leaves fingerprints behind?
ridges
Database that stores fingerprints?
AFIS
What does AFIS stand for?
Automated Fingerprint Identification System
objects or materials that retain characteristics through direct contact
impression evidence
impressions can be identified as either … or … evidence
class; individual
A split on a tire tread is an example of what type of evidence?
individual
A truck is an example of what type of evidence?
class
Knowing a shoe size can help investigators find the … height of individual.
range
made by oils and sweat glands, invisible to the naked eye
latent prints
made by blood, grease, ink, or dirt, visible to the naked eye
patent prints
3- dimensional impression made in fresh paint, wax, soap,ect
plastic Prints
examples of class impression evidence?
brand of shoe
individual impression evidence?
specific patterns
the smallest unit
fibers
made from fibers
textiles
man made fibers (3)
- rayon
- polyester
- acrylic
natural fibers (3)
- cotton
-silk - hemp
What would be direct transfer of hairs and fibers?
from victim to suspect
What would classify a secondary transfer of hairs and fibers?
from source to suspect to victim, or vice versa
Weave and pattern thread count help determine what?
the type of fiber
What can fiber evidence show? (5)
-type
-color
- violence
- suspect location
- point of origin
Hair functions as? (3)
-temperature regulation
- sensory organ
- protection
made up of a protein called keratin
hair composition
Parts of a strand of hair
Cuticle, cortex, medulla
What two parts of a strand of hair protect the cortex and medulla of the hair?
Cuticle and medulla
Benefit of hair being slow to decompose
Allows evidence (including DNA) to be extracted for longer
- Anti B
- A antigen
Blood Type A
- Anti A
- B Antigen
Blood Type B
- A antigen
- B Antigen
- No antibodies
Blood Type AB
- Anti A
- Anti B
- No antigens
Blood Type O
A compatible blood types?
- A
- O
B compatible blood types?
- B
- O
AB compatible blood types?
- A
- B
- AB
- O
O compatible blood types?
- O
- clumping with Anti-A & Anti-D
- no clumping with Anti-B & Control
A+
- clumping with Anti-A
- no clumping with Anti-B, Anti-D, & Control
A-
- clumping with Anti-B & Anti-D
- no clumping with Anti-A & Control
B+
- clumping with Anti-B
- no clumping with Anti-A, Anti-D & Control
B-
- clumping with Anti-A, Anti-B, & Anti-D
- no clumping with Control
AB+
- clumping with Anti-A & Anti-B
- no clumping with Anti-D & Control
AB-
- clumping with Anti-D
- no clumping with Anti-A, Anti-B & Control
O+
- no clumping with Anti-A, Anti-B, Anti-D & Control
O