Chapter 4 - Physical Evidence Flashcards
What are the two kinds of proof used during a criminal trial to answer the questions of guilt or innocence?
direct evidence & circumstantial evidence
What kind of evidence involves eyewitnesses who have, through one or more of their five senses, experienced something relative to the crime in question or its circumstances?
direct evidence
What type of evidence is defined as evidence from which an inference can be drawn and which includes items such as physical evidence?
circumstantial evidence
What are the two broad categories physical evidence can be divided into?
class evidence & individual evidence
Glass , paint, shoe prints, ballistics, fibers and tool marks are good examples of what type of evidence?
class evidence
Fingerprints are a good example of what type of evidence?
individual evidence
Is it possible for class evidence to become individual evidence?
yes
What are the primary sources for identification in regard to ballistics?
inside of the barrel, firing pin, breech face, the chamber and ejector/extractor
______ is the identification of firearms, bullets, cartridges and shotgun shells
ballistics
____ ballistics refers to the functioning of firearms through the firing cycle.
interior
____ ballistics is the study of projectiles in flight.
exterior
if the caliber is not marked on a firearm the investigator should qualify any estimate of the caliber by putting _______ in his or her field notes and noting a measurement across the bore of the weapon in _____ ____ ___ ___.
unknown, fractions of an inch
What test is performed when when you examine adhesive tapes using a scanning electron microscope interfaced with an energy-dispersive x-ray?
gunshot residue examination
What type of reaction leads to a rapid increase in temperature followed by a sharp decrease resulting in a unique spheroidal formation that is not generally observed in the natural environment?
exothermic reaction
What color do relatively fresh blood stains appear to be?
reddish-brown
Over time blood stains can appear to be what colors?
red to black, green, blue or grayish white
What test is used to determine whether or not a stain is blood?
the Kastle-Meyer color test
During the Kastle-Meyer color test, what color does the test strip turn as it reacts with the enzymes in the blood?
deep pink
What are the name of the test strips used for a presumptive field test for blood?
Hemastix
What presumptive test could be used to tell whether blood has once been at the crime scene and since been cleaned up?
luminol
Luminol does not produce color, instead it produces _____?
light
Luminol produces a faint blue glow called what?
luminescence
What advantage does Bluestar have over luminol?
bloodstains can be observed without having to create complete darkness
BLuestar and luminol are both capable of detecting bloodstains diluted up to _______ times?
100,000
What is the final determination needing to be made after you have found and determined a stain to be blood?
Whether it is animal or human
What test is used to determine whether blood found is animal or human?
Precipitin test
What test takes advantage of the fact that antibodies and antigens diffuse or move toward one another on a plate coated with a gel medium made from a polymer called agar and is also another precipitin test?
Gel diffusion
_______ are markings left on a surface by protruding parts of a person or vehicle?
Imprints
________ are made by a person or an object in a material softer than the item of evidence
Impressions
Fingerprints that are bloody and left on a weapon at the crime scene are called __________ prints.
Contaminated
What type of fingerprints can are you able to see with the naked eye?
Plastic prints
What type of prints cannot be seen with the naked eye and need to be developed?
Latent prints
What process is used to develop latent fingerprints found on a porous surface such as paper?
Iodine fuming or ninhydrin process
When developing latent prints with iodine fuming, the fumes react with the amino acids in the print and turn what color?
Purple
If a latent print was left on a smooth or slippery surface what process would be used to develop it?
Cyanoacrylate fuming process
What does AFIS stand for?
Automated fingerprint identification system
What has to be attached to the hair for DNA analysis to be considered?
The root bulb
What is the approximate rate of hair growth?
One centimeter per month
What two groups are fibers classified into?
Natural and manufactured
What are the most common natural fibers?
Cotton and wool
What type of microscope is connected together side by side that allows two samples to be viewed simultaneously?
Comparison microscope
When beginning to compare two fibers what two features would be compared first?
Color and diameter
What are the two types of glass fractures?
Radial and concentric
What type of fracture starts at the center and run outward in a star shaped pattern?
Radial
What type of fracture forms concentric circular crack in the glass around the point of impact?
Concentric
What is more useful a paint chip or smear?
Chip
What is the most that can be determined from paint when comparing two samples?
The control and questioned sources are consistent
