Serology and Bloodstrain anaylsis

Question 1

how is the value of blood iuse as evidence

Answer 1

a) determine if a crime has been committed
b) link a suspect to a scene or victim
c) lead to addtional evidence
d) reconstruct events

Question 2

what is blodstrain pattern analysis

Answer 2

is is the examination of the shapes, locations, and distribution patterns of bloodstains, in order to provide an interpretation of the physical events which gave rise to their origin

Question 3

can blood strain evidence reveal

Answer 3

• Point of origin(s) of blood source
• Speed with which blood left its source
• Position of victim & assailant
• Sequence of events
• Number of blows/shots & type of weapon

Question 4

what are two types of blood testing

Answer 4

presumptive test
confirmatory test yields

Question 5

what is the presumptive test

Answer 5

is highly sensitive but not specific for a particular substance

example - may test positive for
blood but may not be
human blood

• Some false positives are acceptable as long as no false negatives are obtained

Question 6

what is the confirmatory test yield

Answer 6

– Specific to that substance
– May be less sensitive
– A few false negatives are acceptable, as long as no false positives are obtained
– For blood- DNA fingerprinting

Question 7

what color change happen in the presumptive test

Answer 7

a) stain may or may not be visible
PHENOPHTHALEIN ( kastle meyer test )

Question 8

what is luminol

Answer 8

luminol ius the reactionin th epresence of hemogoblin, when an oxidizer is applied
a) reaction result in a blue white to yellow green luminscence

Question 9

why is luminol is use in the prepumstive test

Answer 9

• utilized as a presumptive test for blood
• enchance the impression in blood on various surface
  -used to check for latent prints or blood strain where area has been cleaned by suspect or others

Question 10

what does luminol react to

Answer 10

luminol is not specific for human blood but also react to animal blood. it can alsi react to bleach leading to false postive

Question 12

passive bloodstain

Answer 12

are clots , drop, flow and pooling of the blood

Question 13

what is viscosity

Answer 13

• mutal attraction of molecules of bloof and the resistance to change of form or flow, “ thickness” - think of milkshake compared to regular milk

Question 14

what is terminal velocity

Answer 14

is the blood falling through aur increase velocity until air resistance equal downward gravitional pull - at that point , ( as fast as it can go )

Question 15

What are factor that can affect the look of the stain

Answer 15

volume: more volume = larger stain
height= increased of hieght will produce more edge disruption, and increased diameter within first 7 feet.

Question 16

can suface affect blood stain

Answer 16

yes, the rougher the surface is the more dispution iof the stain is. The hard smoother suface it is the less dispurtion there is

Question 17

define angle of impact

Answer 17

angles the blood struck the suface

Question 18

whaare void in blood pattern

Answer 18

is the absence of blood stain in an otherswise continous pattern.item removed after blood was deposited .

Question 19

define projected or impacted blood stain

Answer 19

this is the spatter, splash, cast off stain ad arterial spurts or gushes of blood

Question 20

define spattered blood

Answer 20

a random distribution of bloodstains that vary in size and that may be produced by a variety of mechanisms- Usually with applied force, not a simple drop

Question 21

why is spattered blood is significant

Answer 21

• Allows for determination of an area or location of the origin of blood source
  – If found on suspect’s clothing, may place person at scene of violent altercation
  – May allow the determination of the mechanism that created the pattern

Question 22

can the amount of force influnence spatter

Answer 22

yes, it influence the amoutn of quality of aviable blood that can spatter

Question 23

define the direction of travel

Answer 23

is the Determined the direction of travel by observing the tail or scalloped edges of the ellipse

Question 24

what can help determine the direction of travel

Answer 24

The tail or edges will point in the direction of travel

Question 25

what is a wve cast off

Answer 25

Tail of elongated stain points in direction of travel. meaning where the blood strain started and kept traveling

Question 26

hwo do you deterine the point of convergence

Answer 26

• The common intersection to which a bloodstain pattern can be projected
• This convergence location is an area, not an exact point- 2 dimensional only