Forensics Winter Exam Content Flashcards by Keirsten Rogers

property of physical evidence that connects an individual or thing to a group that share similar characteristics

class evidence

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property of physical evidence, narrows to one individual

individual evidence

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examples of class evidence? (3)

shoe prints
blood type
hair (w/o the follicle)

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examples of individual evidence? (3)

DNA
hair (w/ the follicle)
fingerprints

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the initial location

primary crime scene

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secondary location

secondary crime scene

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evidence used to imply a fact but not prove it directly

circumstantial indirect evidence

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material that comes from a proven or known source

control sample

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very small pieces of evidence

trace evidence

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evidence that (if true) proves an alleged fact, such as an eyewitness account of a crime

direct evidence

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What are most wrongful convictions the result of?

faulty eyewitness testimony

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when a person comes into contact with an object (or another person) across transfer of physical evidence can occur

Locard’s exchange principle

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Why is it important to separate witnesses at the crime scene?

reduce the likelihood of them reporting into things they have not directly observed

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the unbroken paper trail that follows evidence from the crime scene, through analysis, and all the way to the court room

Chain of Custody

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5 components of a crime scene sketch?

direction
measurements
evidence
markers
correct object placement

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What type of evidence has allowed the Innocence Project to free individuals from prison for wrongful convictions?

DNA evidence

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objects found at the scene of a crime

physical evidence

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materials or substances of bodily fluids and tissues; evidence from an organic source human, plant, or animal

biological evidence

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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

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red blood cells

erythrocytes

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platelets

thrombocytes

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white blood cells

leukocytes

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substances on cells that trigger an immune response

antigens

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proteins that attach to red blood cells as an immune response

antibodies

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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?

Most common finger print?

loops

How many deltas are in a loop?

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