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Lecture 3

FSCI 1010U Lecture Notes - Lecture 3: Cyanoacrylate, Finger Ridges, Dermis

Course Code
FSCI 1010U
Nelson Lafreniere

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Forensic Science Lecture 5 01.27.16
Pattern and Impression Evidence
The Importance of Fingerprints
Today, the fingerprint is the pillar of modern criminal identification
They are useful for two major reasons:
oFingerprints are unique to every individual
oFingerprints do not change
Unequivocal identification is possible
What are Fingerprints?
The deposition of friction ridges
oAppear on palms, soles, and the ends of fingers and toes
oRidges provide friction between the grasping mechanism and whatever it grasps
oRidge: A single curved segment – A hill
oFurrow: Region between two adjacent ridges – A Valley
oPore: Found on ridges
Produced by:
othe deposition of sweat
oby a finger contaminated with another material
oby a finger that has been pushed into a soft material such as putty
Stamp of the ridge detail on the skin surface
Types of Fingerprints – Visible
Made by fingers touching a surface after the ridges have been in contact with a colored
Patent – meaning obvious or evident – occur when fingers are contaminated with
Plastic - Made when a finger touches or presses against a soft-pliable surface
Types of Fingerprints – Latent
Once the finger touches a surface, sweat and/or oil present on the finger ridges are
transferred to that surface, leaving an impression
Prints deposited in this manner are invisible to the eye and are commonly referred to as
latent invisible fingerprints
Friction ridge examination is the preeminent method of individualization in forensic
How Long do Fingerprints Last?
Plastic prints remain as long as the impressed material is structurally intact
Prints left in a medium, such as blood or dust, are fragile and do not last long
Latent prints, in a proper environment, can last for years
The age of a print is almost impossible to determine

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Forensic Science Lecture 5 01.27.16
How Well is a Fingerprint Formed?
A number of parameters will determine how well a fingerprint is formed:
oThe surface upon which the print is being made
oThe pressure applied
oThe length of time of contact
Of all, the length of time is the most important
Classification of Fingerprints
General patterns of friction ridges allow for their Fingerprints are divided into three
classes on the basis of their general pattern:
5% 60-65%
There are several types of whorls – they are the most complex
Loops and Whorls contain cores and deltas
Core- Approximate center of the fingerprint
– Location of max curvature
Delta – Point on a ridge where there is a
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