More Trace Evidence Flashcards
What are some examples of marks and impressions that can be left at the crime scene?
Fingerprints Footwear impressions Bite marks Tool marks Tyre marks
What is dactyloscopy?
Study of fingerprint identification
What is the development of fingerprints?
Formation- early fetal life
Uniqueness- even identical twins have different fingerprints, 64 billion to 1 chance that individuals can have the same fingerprints
Persistance
What are the classifications of fingerprints?
Ridges and patterns- ridges for grip, lots of nerve endings, helps to keep you cool
Loops
Arches
Whorls
Approximately how many people in the population have loops?
60%
What are loops divided into?
2 groups- divided by direction loops slant
What are the two types of loops?
Ulnar Loop
Radial Loop
What is an Ulnar Loop?
This is the most common type of fingerprint
What is a Radial Loop?
The loop slants towards the radius (the thick bone of the thumb side of the hand)
What is important to remember about direction of loops?
Direction of loop would be opposite way round of the left hand
What percentage of people have arches?
approx 5%
What groups can arches be divided into?
Two groups-
Plain Arch
Tented Arch
What is a Plain Arch?
A mound like pattern
What is a tented Arch?
Looks like a church steeple
How many groups can Whorls be divided into?
4 groups- Plain Whorl Central Pocket Whorl Double loop Whorl Accidental Whorl
What is plain whorl?
Circular spiral pattern
What is a central pocket whorl?
A tight circular pattern in the centre of the fingerprint
What is a double loop whorl?
Two looped patterns
What is an accidental whorl?
An irregular circular pattern
How can you identify a print?
Crime Scene
Sweat in fingers leaves impression
What is the name for the surface a fingerprint is left on?
Substrate
What is the name for the fingerprint?
Matrix
What are the types of fingerprints?
Latent
Visible
Plastic
What is a latent fingerprint?
Invisible to the naked eye
What is a visible fingerprint?
Clearly seen, positive (leave a mark on surface e.g. mud or blood) or negative (e.g. thin snow, snow transferred to tyre)
What is a plastic fingerprint?
3D prints e.g. soft surface, clay, deep mud, deep snow produce impression
What is ACE-V?
Analysis- fingerprint powders, intelligence gathering
Comparison- compare fingerprint to database
Evaluation- determination of uniqueness to suspect
Verification- independent analysis by 2 fingerprint experts subjective fingerprints
How can you recovery footprints?
Photograph, chemical, powders to highlight print, produce a cast if there is a 3D print
What sources can you get bite marks for?
Food, suspect or victim, skin, objects i.e. apple, chocolate, small ridges of teeth, different patterns
Who examines bite marks?
Forensic odontologist
How do you preserve bite marks?
Cast (rubber base material), photographs
How can you compare bitemarks with suspect?
Cast of suspect teeth, have a look at biting edges (clear film on bite source), DNA from saliva
How can toolmarks be analysed?
E.g. saw, screwdriver
Comparison of marks
Microscopy
What are tyre marks?
Formed from tread on tyres
What can tyre marks lead to?
Information can lead to make and specification of tyre
