L7: physical evidence and lab Flashcards
list the different types of evidence
- associative
- class
- electronic
- latent
- trace
- circumstantial
- direct
associative evidence
any evidence that places an individual at a scene or with the victim
examples of associative evidence
- latent f.print left on an object
- semen from sexual assault
- paint transfer during automobile accident
- fibre left from contact with clothing items
- blood from physical injuries
- GSR
class evidence
evidence that requires classification into a more narrow range
non-individualizing characteristics
examples of class evidence
- overall f.print patterns
- size of shoe
- tire tread make
- shoe tread make
electronic evidence
information and data transmitted and/or stored in any electronic devices
typically involved in crimes such as fraud or child pornography
examples of electronic evidence
- computers
- cell phones
- USB/flash drives
latent evidence
not visible to the naked eye without some form of enhancement or development [ALS or chemical treatment]
examples of latent evidence
- fingerprints
- blood
- trace
- fibre
trace evidence
extracted from another substance and is inn very small quantity [often not visible to the naked eye]
examples of trace evidence
- fibers
- hair
- GSR
- paint
circumstantial evidence
- evidence that relies on an inference to connect it to a conclusion or fact
- allows for more than one explanation, can be interpreted differently by different individuals
- most types of physical evidence fall under circumstantial evidence
examples of circumstantial evidence
- fingerprints
- witness testifies they only heard the sounds of a gunshot and ran around the corner to find the defendant standing over the victim with a gun
direct evidence
direct proof of fact
examples of direct evidence
- eye witness account [i.e. witness testifies they saw the defendant shoot the victim]
why collect physical evidence
- shows that a crime has been committed
- may show the key elements of a crime
- links suspect with the scene and/or victims [locard’s principle]
- corroborates statements
- exonerates the innocent
can someone be convicted solely based on circumstantial evidence
yes [most evidence is circumstantial]
what is locard’s exchange principle
‘every contact leaves a trace’
something is left, and something is taken
how does cross contamination occur
when the biological or trace evidence from one evidentiary item contacts and contaminates another piece of evidence
impacts integrity, validity, credibility of the evidence and the handler
how do you maintain integrity of an item
- package separately in paper bags
- evidence stored in secure lockers
- changing gloves during collection
- chain of custody
describe chain of custody
a complete and unbroken record of the following information
- where was it located?
- who initially seized it?
- date and time it became evidence/seized
- who has possession of the evidence?
- what has been done to the evidence?
- where is the evidence currently being stored?
