Physical Evidence - Collection and Analysis Flashcards
What is evidence?
Refers to anything that can give or substantiate information in a legal investigation.
Why is evidence important (3)?
Provides a clear direction for investigators to form leads
The quantity of evidence establishes the case’s credibility in court affecting judge and jury
Certain types of evidence bring with it the testimony of expert witness
What are the 7 types of physical evidence?
Associative
Class
Electronic
Latent
Trace
Circumstantial
Direct
What is associative evidence?
Any evidence that places an individual at a scene, with the victim, or in possession of an item
Give examples of associative evidence.
Latent fingerprint left on an object
Semen from an SA
Paint transfer during car accident
Fibers left from contact with clothing items
Blood
What is class evidence?
Evidence that requires classification into a more narrow range
Can class evidence be used for identification purposes?
No, only exclusion
Give examples of class evidence.
Overall fingerprint patterns Size of shoe
Tire tread make
Shoe tread make
What is electronic evidence?
Information and data transmitted and/or stored in any electronic devices
What types of crimes is electronic evidence typically involved in?
Fraud, child pornography
Give examples of electronic evidence.
Computers
Cell phones
USB/flash drives
Printers
Trackers on vehicles
What is latent evidence?
Not visible to the naked eye without some form of enhancement or development
Give examples of latent evidence.
FIngerprints
Blood
Trace
Fibers
What is trace evidence?
Extracted from another substances and is in very small quantity (microscopic), often not visible to the naked eye.
Give examples of trace evidence.
Fibers
Hair
GSR
Paint
What is direct evidence?
Offers direct proof of fact
Give an example of direct evidence.
Eye witness account
What is circumstantial evidence?
Evidence that relies on an inference to connect it to a conclusion or fact.
Give 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
What are the 5 reasons for collecting physical evidence?
Shows that a crime has been committed
May show the key elements of the crime
Links suspects with scene and/or victims
Corroborates statements
Exonerates the innocent
Can someone be convicted solely based on circumstantial evidence?
Yes. Most evidence is circumstantial
What is cross contamination?
When biological or trace evidence from one evidentiary item contacts and contaminates another piece of evidence.
What is Locard’s Exchange Principle?
EVERY CONTACT LEAVES A TRACE
Something is left and something is taken
How do you maintain the integrity of physical evidence?
Package separately in a paper bag
Evidence stored in secure lockers
Changing gloves during collection
Chain of continuity
PPE
Why should evidence be stored in a paper bag?
Wet/damp items can’t breathe in plastic leading to mold
What is the information included in chain of custody (5)
Where was it located?
Who initially seized it and under what seal number?
Date and time it became evidence/seized
Who had possession of the evidence/where is it stored?
What has been done to the evidence?
What are the 5 sections of CFS?
Biology
Chemistry
Documents
Physical sciences
Toxicology
What type of analysis is performed in the biology sector of CFS?
Body fluid identification
DNA profiling
What are the 2 streams of biology at CFS?
Major crime
High volume program
What type of offences are delt with in major crime?
Primary
What type of crimes does the CCC define as primary offences?
Assault
Homicide
SA
Attempted murder
Shootings
What type of offences are dealt with in the high volume program?
Secondary
What are classified as secondary offences?
Theft
Mischief
Stolen vehicles
Drug and weapons offences
Why are BnEs dealt with in the high volume program despite being classified as a primary offence?
Happen so often
Outline the 4 steps in swabbing wet bloodstains.
Put on gloves and make sure mask is being worn
Swab the bloodied area
Properly label the swab and include appropriate case information
Allow the swab to air dry for 24 hours in a drying cabinet under seal before submission to CFS
When swabbing wet bloodstains, does the swab need to be fully saturated?
No
How do you properly label a swab?
S1 or 1-S1 if swab is from item one
Outline the steps in swabbing dry bloodstains.
Put on gloves and mask
Moisten cotton tip with 2-3 drops of distilled water
Swab the bloodied area
Properly label the swab and include appropriate case information
Allow the swab to air dry for 24 hours in a drying cabinet under seal before submission to CFS
What type of samples does the biology sector of CFS use for comparison samples?
Blood
Buccal
Pulled head hair
Discard
Familial
What type of materials are examined in the chemistry sector of CFS
Oils and lubricants
Explosives
Fibres
Metals
Paints
Glass
Tape
How do prevent loss of small particles when collecting paint?
Druggists fold
What is the window for collecting GSR on hands?
8 hours due to washing, wiping, using objects
Are GSR samples taken from victims?
No. We already know they’ve been shot
How must fire evidence samples be packaged?
In mason jar into Nylon bag with goose neck seal
How must soul and vegetation fire evidence be stored?
In refrigerator
Should fire evidence be air dried?
No
How full should mason jars with fire evidence be?
3/4
How should liquid fire evidence be packaged?
In teflon type vials
What does the documents section of CFS do?
Compares handwriting and signatures to identify or eliminate a particular writer
Compares pens, pencils, inks, paper and printing processes used to produce them
Outline the steps of a firearms submission.
Fingerprinting and swabs for DNA done first
Remove any cartridge from the chamber and render firearm safe
Remove magazine
Package firearm and ammo separately and package in a rigid box
Why must firearms found in water be submitted in a sample of the water they were found in?
Prevents corrosion/rusting
What type of cases would toxicology be used in?
Death investigations
Impaired driving
Sexual assaults
Fire death
Homicides
What is toxicology?
Analysis of body tissues and fluids for the presence of drugs/alcohol
What is collected for toxicological analysis in a coroner’s death investigation?
Heart + femoral blood
Urine
