More Trace Evidence Flashcards by Emma Strang

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

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What is dactyloscopy?

Study of fingerprint identification

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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

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What are the classifications of fingerprints?

Ridges and patterns- ridges for grip, lots of nerve endings, helps to keep you cool
Loops
Arches
Whorls

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Approximately how many people in the population have loops?

60%

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What are loops divided into?

2 groups- divided by direction loops slant

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What are the two types of loops?

Ulnar Loop

Radial Loop

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What is an Ulnar Loop?

This is the most common type of fingerprint

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What is a Radial Loop?

The loop slants towards the radius (the thick bone of the thumb side of the hand)

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What is important to remember about direction of loops?

Direction of loop would be opposite way round of the left hand

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What percentage of people have arches?

approx 5%

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What groups can arches be divided into?

Two groups-
Plain Arch
Tented Arch

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What is a Plain Arch?

A mound like pattern

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What is a tented Arch?

Looks like a church steeple

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How many groups can Whorls be divided into?

4 groups-
Plain Whorl
Central Pocket Whorl
Double loop Whorl
Accidental Whorl

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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