Ch 4 Physical Evidence Flashcards
What is the greatest possibility of error when searching for weapons at a crime scene?
Ignoring common items of furniture or equipment at the scene as suspect weapons
The removal of spent bullets without damage to the original condition is an example of what?
Postmortem forensic science
Valuable evidence that typically gets recognized
Bloodstains on clothing and other objects
Blood splashes and and blood drops help to narrow ….
The size of the suspect group,
Support identity when a an sp is located,
And plot the movements of the v and the assailant
Relatively fresh bloodstains generally appear to be ….
Reddish-brown in color
The question that often must be answered of bloodstains?
Whether the stain is blood or some other substance
How is the determination of whether or not a stain is blood?
Preliminary test color, kastle-Meyer color test
This test is based on the reaction with enzymes in the blood which causes the test strip to turn a deep pink color
Kastle-Meyer color test
Theses test strips are a useful presumptive field test for blood
Hemastix
Test strips used with the Kastle-Meyer color test
Hemastix
Theses are a useful presumptive field test for blood
Hemastix
Drop sizes of blood increases with the
Distance of the fall
The tails or pointed ends on bloodstains indicate
The direction of movement
The round edges of blood stains face
The source of the bleeding
Another ? That must be answered is whether at one time blood was present at the crime scene…
And has since been cleaned up
Presumptive test that uses light rather than color as it reacts with blood
Luminol
Luminol helps identify whether blood at a scene…
Was cleaned up
Faint blue glow after spraying luminol
Luminescence
New trademark name that may be used in place of luminol
Bluestar
T/f
A room does not need to be darkened in order to use luminol
False
Advantage of bluestar over luminol
It’s reaction with a bloodstain can be observed without having to create complete darkness
Both of these presumptive tests are extremely sensitive and are capable of detecting bloodstains diluted up to 100,000 times
Blue star and luminol
Final determination in blood evidence
Whether it is human or animal origin
These tests are based on the reaction when animals, usually rabbits, are injected with human blood
Precipitin test