Biological Evidence

Question 1

How can direction of a bloodstain be determined?

Answer 1

The pointed end “tail” points in the direction of impact

Question 2

How is angle of impact determined?

Answer 2

arcsin (width of ellipse/length of ellipse)

Question 3

If a blood drop is circular what can you determine?

Answer 3

That the blood drop hit the surface at a 90 degree angle

Question 4

What is Locard’s Exchange?

Answer 4

when entering an environment one will add and take away something from that environment

Question 5

How do you package biological evidence?

Answer 5

in PAPER!!!

Question 6

List some examples of class evidence.

Answer 6

fibers, paint, most shoe/tire impressions

Question 7

List some examples of individual evidence.

Answer 7

fingerprints, hair, blood, semen, DNA, bullet w/ rifling

Question 8

How is length of body measured?

Answer 8

from heel to crown

Question 9

What happens to bodies in water?

Answer 9

They swell more

Question 10

What happens to a body in a dry environment?

Answer 10

it becomes mummified

Question 11

What is adipocere?

Answer 11

grave wax

Question 12

When does adipocere form?

Answer 12

in cold/wet conditions

Question 13

What can blood spatter be used for?

Answer 13

to corroborate testimony given

Question 14

Ways to spot a grave site.

Answer 14

• Extra soil
• dying/thriving plants
• depression in soil
• shallow grave
• lots of insect/animal activity

Question 15

When does a blood drop have scalloped edges?

Answer 15

when it lands on a textured surface

Question 16

What can be inferred from a vertical drop?

Answer 16

That the object/person was not moving when the blood drop formed

Question 17

What is terminal velocity?

Answer 17

the speed at which a vertical drop of blood will not travel any further

Question 18

What sort of trauma would cause high velocity spatter?

Answer 18

Gunshot

Question 19

What sort of trauma would cause medium velocity spatter?

Answer 19

blunt force trauma

Question 20

What sort of trauma would cause low velocity spatter?

Answer 20

someone who was punched (fist)

or cast off

Question 21

If there are 4 cast off patterns on a wall, how many blows were given?

Answer 21

A minimum of 5 blows occurred

Question 22

What is chemiluminescence?

Answer 22

the process by which light is emitted as a product of a chemical reaction

Question 23

What is fluorescene?

Answer 23

occurs when a substance is exposed to certain wavelengths of light (like short wave UV) and long wave light is emitted back

Question 24

What chemical can be used to find blood that has been painted over?

Answer 24

Luminol

Question 25

What is agglunation?

Answer 25

the clumping of particles

Question 26

What is a secretor?

Answer 26

individuals who secrete ABO biochemical characteristics into body fluids (saliva, semen, vaginal fluid)

Question 27

What is azoospermia?

Answer 27

semen lacking spermatozoa

Question 28

What is SAP (seminal acid phosphate)?

Answer 28

analysis of stains for protein components of seminal fluid

Question 29

Confirmatory tests for semen.

Answer 29

- microscopic I.D of sperm - prostate-specific antigen (PSA/P30) - picroindigocarmine (PIC) heads turn red and tails turn purple

Question 30

What characteristics make a good presumptive blood test?

Answer 30

- sensitive to heme - reliable, stable, relatively cheap, relatively non-toxic - meets Frye standards of admissibility - is non destructive to evidence - is non destructive to the crime scene

Question 31

What can cause a false positive on a presumptive blood test?

Answer 31

- Vegetable and animal peroxidases | - oxidants

Question 32

How would you collect dried blood evidence on a non porous surface?

Answer 32

scrape into a sterile container with a razor

Question 33

How would you collect dried blood on a porous surface?

Answer 33

submit the article as is or if very large remove a portion and submit that

Question 34

What is elution?

Answer 34

process of extracting one material from another by washing with a solvent

Question 35

Examples of biological trace evidence

Answer 35

- hair/fur - saliva - semen

Question 36

Where is trace evidence found during sexual assult?

Answer 36

- on the victim - on the suspect - at the scene

Question 37

What is the pharmaceutical fold? When is it used?

Answer 37

- it is when trace evidence is placed into paper folded in half and then placed in a secondary container. - It is used to prevent loss of trace evidence such as hair/fibers.

Question 38

What type of crime is associated with saliva as evidence?

Answer 38

violent crimes (rapes/murders/etc)

Question 39

What does hair root look like in a forced removal?

Answer 39

club shaped

Question 40

What does a hair root look like when naturally shed?

Answer 40

bulb/ round shaped

Question 41

What is y-STR ?

Answer 41

a set of specific STR markers associated with male Y-chromosome

Question 42

What is abandoned DNA?

Answer 42

DNA left on drink cups/cigarettes that have been throw out or abandoned. These may be collected without suspects knowledge

Question 43

What is a DNA dragnet?

Answer 43

DNA samples taken form everyone in a large area with hopes to find the suspect among them.

Question 44

What leads to degradation of DNA?

Answer 44

- time - temperature - humidity - light (UV/natural)