Week 3 Flashcards
What is evidence
Something which shows that something exists or is true
Visible sign of something
Material that is presented in Court of Law to help find the truth about something
Three types of evidence
1) Testimonial
- witnesses, video or audio
2) Documentary
- cheques, documents, photos, certificates
3) Physical
- finger/foot/tire impressions, physical match
Locards Exchange Principal
When an object or person comes into contact with an object or another person, a cross-transfer of physical evidence occurs
4 responsibilities of evidence from collection until Court
1) Identify each piece of evidence
2) Describe exactly where it was found
3) Prove continuity
4) Describe any changes:
- Physical damage due to storage
- Spillage/evaporation
- Change in physical appearance
Good sources for DNA
Blood
Saliva
Hair root
Tooth pulp
Bone marrow
Skin cells/muscles
Semen
Nasal secreations
What is Linkage in photography
Links your photographs one to the other by using a common object which is present between one photograph and the one that follows it.
3 types of photos for Forensic photography
1) Overall
Shows how the specific crime scene fits into and relates to the surrounding area; shows general scene
2) Midrange
Shows items of evidence in relation to other fixed features within the immediate area of the item
Can be linked back to the overall shot to show its location within overall scene
3) Close-up
- without scale
- with scale
Primary object or item of evidence alone; fills the screen with the object of interest to maximize detail
What is Fill Flash
A method used to lighten shadowed areas to show an area of interest
Ie: exhibits that are in shaded/dark areas
2 types of 2D footwear impressions
1) Transfer (positive) impressions:
Transfer of material acquired by the shoe during prior steps that is then redeposited
2) Take-away (negative) impressions:
Contact areas of outsole remove material from substrate
2 types of footwear impression ORIGIN
1) Wet-origin impressions:
Involve moisture; wet or dry matrix transferred to wet or dry substrate
2) Dry-origin impressions:
Dry matrix transferred to dry substrate (tend to be very fragile)
Difference between Grazed and Oblique lighting
1) Grazed:
Parellel to surface; dust particles reflect the light;
Dust impressions best located / viewed / photographed
2) Oblique:
Between 0 and 90 degrees
NOT parellel to the surface
Why use a tripod for ACAP’s
1) Better control of flash
2) Ensures lens/sensor parallel to impression
3) Frees up hands: provide shade, use flash, reflect soft light, etc
4) Maximize depth of field
5) Ability to do timed exposure
6) Consistent height with multiple impressions
How do you take an ACAP
1) Flash on sync cord
2) Shutter release cable
3) Fixed 60mm lens
4) Manual focus (NOT auto)
5) Adjust Aperature to maximize depth of field
6) Fill frame/center impression
7) Use ‘L’ ruler
Why do you put a reverse F# on a Gel and ESDL lifter
A reminder the impression Is laterally reversed
ie: unlike fingerprints which use transparent lifters, Gel and ESDL are solid and therefore the imression you see on the lifter is reversed.
When you are in photoshop, the reverse ‘F’ number reminds you to flip the image.
