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Canada (511,183)
FSC239Y5 (435)
Ragab, H (11)
Lecture 3

FSC239 Lecture 3.docx

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Forensic Science
Course Code
Ragab, H

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September 25 ,2012 FSC239Y5 Lecture #3 Footwear Identification Detection and Collection Detection:  Visible  Latent  Lighting  Powders  Chemistry Collection:  Photography  Fingerprint tape  Dental stone lift (The Knaap Process)  Dental stone casts (soil and snow)  Sulfur casts Benefits – Investigative Aid  Type of Shoe  Pattern Design  Number of suspects  Connections to other crime scenes  Sequence of events - directionality 2D vs. 3D Impressions  Two Dimensional: o An impression which for all practical purposes has the dimensions of length and width but not a significant depth  Three Dimensional: o An impression of length witch and depth o Camera has to be parallel with the impression General or “Class” Characteristics  An intentional or unavoidable characteristic that repeats during the manufacturing process and is shared by one or more other shoes or tire. o Tread pattern o Type of footwear o Size o Wear pattern o Defects indicative of the manufacturing process Accidental or “Individual” Characteristic th September 25 ,2012 FSC239Y5 Lecture #3  The result when something is randomly added to or taken away from the original structure of the shoe or tire that either causes or contributes to making that shoe or tire unique  Physical shapes  Spatial relations  These provide the uniqueness and individualizing strength Identification Process Fingerprints vs. Footwear  Fingerprint conclusions o More definitive  3 Conclusions  It IS  It ISN’T  Not enough information  Footwear conclusions o Manufacturing  Still in production  Years produced  How long since production ended  How many made  Why the difference? Direction or Enhancement  Light : ambient, white, oblique ALS Laser  Fingerprint powder  Chemistry(blood reagents, Bromophenol Blue, Potassium Thiocyanate, iodine fuming, Leucomalichite Green, Paint or snow paint wax) Labelled Photography (for comparison purposes)  Three basic rules  Scale be same plane as the lowest part of impression  Lens perpendicular (90°) to impression  Mark impression with designation number (F1, F2) Collecting 2D Footwear  Physically removing substrate with the impression on it and preserving it (floor tiles, etc)  Fingerprint powder enhancement o 4” finger print tape on acetate or backing card o Polivinylsiloxane o Gel lifter o Dental stone (the knaap process)  Comes in powder form.  Add water  Pour it into impression  Let it harden In snow th September 25 ,2012 FSC239Y5 Lecture #3  Temperature  Type of snow (crystalized, granular, wet, slush, ice)  Exposure to direct sunlight Dental stone (the knaap process)  Get the dental stone at the same temp as the snow  Has long cooling process Casting With Sulfur  Melt sulfur at low temp(160degrees) on a foot stove  Long process of getting it ready ahead of time  Cools instantaneously Fingerprints What are Fingerprints?  It is an impression left by the friction ridges (FR) of a human finger.  Fingerprints are the traces of an impression from the friction ridges of any part of a human hand. A print from the foot can also leave an impression of friction ridges  Fingerprints are never changeable  Destroyable but not changeable  If damage reaches dermal papillae, only scar will be left.  If damage does NOT reach dermal papillae, skin will regenerate in same pattern as it was before.  Fingerprints are inherited History of fingerprints  Used as signatures in ancient Babylon in the second millennium BCE Sometime before 851CS, Chinese merchants using fingerprints to authenticate loans   Alphonse Bertillon o (Invented - 1879)Anthropometric system to identify individuals  Sir Frances Galton o 1882  Sir Edward Henry o 1880 o Developed alternate classification system Adopted in England o System invented by him still used today (FBI)  In Canada o 1904 Development and genetics of fingerprints  During weeks 10 thru 17 of gestation ridges are formed on the epidermis  Are static and do not change with age  The pattern changes in size, as person grow
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