The Chemistry of Latent Print Development Techniques Fingerprints In the Legal Arena The Chemistry of Latent Print Development Techniques

Portrait Parle’ A Verbal description of a perpetrator’s physical characteristics and dress provided by an eyewitness

Bertillon’s Anthropometry1883 Relied on Precise Skeletal Measurement Rested on the Premise That Skeletal Measurements Were Fixed After Age 20 Utilized Photographs as Well as Physical Description

Bertillon’s Fall From Favor Will West versus William West Case Both men sent to Leavenworth Only way to tell them apart was fingerprints!

Early use of Fingerprints 1. Chinese- Used fingerprints to sign legal documents 2.William Herschel- Required Indian citizens to sign contracts with imprints 3. Henry Fauld- 1880, suggested that skin ridge patterns could furnish infallible proof of identification

History Cont’ 4. Francis Galton-1892 published 1st book on finger prints assigning 3 patterns ( loops, whorls, arches) 5. Sir Edward Richard Henry, 1897- developed modern system of classification still being used USA and Scotland 6. 1901- US adopted fingerprints use

Daubert Rules of Admissibility 1999 – fingerprint admissibility challenged in United Sates v Byron Mitchell Defense attorney argued that under guidelines cited in Daubert, fingerprints could not be proven unique Daubert hearing took 4 ½ days

Judge Determined 1). Human friction ridges are both unique and permanent 2). Human friction ridge skin arrangements are unique and permanent

The Primary Classification System Part of the Henry System (basis of system used by FBI) Using this classification system – all fingerprint cards in existence can be divided into 1,024 groups Need to determine where the whorls are on “fingerprint pairs”. See text p. 396

Primary Classification System Pair up the fingers like this: r thumb & r index, r middle & r ring, r little & l thumb, l index & l middle, l ring & l little After establishing pairs, place the first one in the denominator, the second in the numerator to create a fraction r index r ring l thumb l middle l little r thumb r mid r little l index l ring

Look for the Whorl Patterns Whorls in the first pair are given a value of 16 Whorls in the second pair, 8 Whorls in the third, 4 Whorls in the fourth, 2 Whorls in the fifth, 1 Now add the numbers together and add 1 to both the numerator and denominator

PRACTICE the Primary Classification System

Fundamental Principles of Fingerprints 1st Principle: A fingerprint is an individual characteristic; no two fingerprints have yet to possess identical ridge characteristics ( FBI has nearly 50 million records in the database)

How are fingerprints formed in the womb? | Ask Dr. Oz

Types of Fingerprints Left at the Scene Latent – invisible until chemically treated Plastic – left in soft material such as putty, wax, soap Visible – fingers touch blood, dirt, grease or paint and then touch a surface

2nd Principle Formed in the human fetus on the Dermal Papillae A fingerprint remains unchanged during an individual’s lifetime Formed in the human fetus on the Dermal Papillae

3rd Principle Fingerprints have general ridge patterns that permit them to be systematically classified

Iodine Fuming Iodine “sublimes” Appropriate for porous surfaces, like paper Must be photographed or “fixed” since prints will fade Iodine “sublimes” Resulting vapor combines with the Na+ ions in the print to form NaI

Ninhydrin Used on porous surfaces Reacts with the amino acids in the fingerprint Results in a blue-purple color

Superglue fuming Used on non-porous items such as metals, electrical tape, leather and plastic bags Superglue is about 98-99% cyanoacrylate ester a chemical that when heated will a create a fume that will adhere to a print

Fluorescence Expose fingerprints to laser light Some components of perspiration will fluoresce They absorb light and remit the light in longer wavelengths Done in darkened room

Chemically Induced Fluorescence Zinc Chloride after Ninhydrin Rhodamine 6G dye after super glue fuming Increases sensitivity to light exposure Can now use high intensity alternate light source (ALS) instead of laser Halogen or xenon-arc light passes through fiber optic cable and filters

DFO Replacement for ninhydrin 1,8-diazafluoren-9-one Has been shown to develop 2.5 times more latent prints on paper than ninhydrin

Preserving Prints Once latent print is visualized, must be photographed