THE SCIENCE OFFINGERPRINT
IDENTIFICATION- or -
How to Make Your Point in the Courtroom!
Prepared by:David “Ski” Witzke
Vice President, Sales & MarketingPC Pros MORE HITS ®
The Science ofFingerprint Identification
The first misconception about latent printidentification is:
Latent print examinersdon’t just count points!
So what’s my point?Latent print identification relies on threelevels of detail NOT just points!
– Level 1 detail -- Ridge flow (patterns)– Level 2 detail -- Ridge formations (ridge
endings, bifurcations, dots, or combinationsthereof)
– Level 3 detail -- Ridge path deviation (ridgestructure or formation, which includes ridgewidth, shape, pores and other details)
Level 1, 2 and 3 Details... a thumbnail explanation of terms coined by David Ashbaugh
Level 1 DetailRidge Flow
Level 1 DetailRidge Flow
Ridge flows make up threeRidge flows make up threedistinct pattern types:distinct pattern types:
•• LoopsLoops•• ArchesArches•• WhorlsWhorls
Level 1 DetailPattern Types
Left slant loopLeft slant loop
Right slant loopRight slant loop
Plain archPlain arch
Tented archTented arch
WhorlWhorl
Double Loop WhorlDouble Loop Whorl
Level 2 DetailFriction Ridge Formations
Friction skin ridges on the hands and feet createFriction skin ridges on the hands and feet createdistinctive features that are grouped into threedistinctive features that are grouped into threebasic characteristics (also known as “points”):basic characteristics (also known as “points”):
•• Bifurcations (or the splitting of a singleBifurcations (or the splitting of a singleridge into two ridges)ridge into two ridges)
•• Ridge endings (or point at which a ridgeRidge endings (or point at which a ridgeends)ends)
•• DotsDots
Level 2 DetailLevel 2 DetailFriction Ridge FormationsFriction Ridge Formations
Level 3 DetailLevel 3 Detail Ridge Path Structure Ridge Path Structure
Latent Print Examiners are allowedto make positive identifications
1. With appropriate training2. With appropriate experience3. With appropriate ability4. When using the scientific procedure of
ACE-V• Analysis• Comparison • Evaluation • Verification
The Scientific Methodologycalled ACE-V
•• AnalysisAnalysis – the qualitative and quantitative assessmentof Level 1, 2, and 3 details to determine their proportion,interrelationship and value to individualize.
•• ComparisonComparison – to examine the attributes observedduring analysis in order to determine agreement ordiscrepancies between two friction ridge impressions.
•• EvaluationEvaluation – the cyclical procedure of comparisonbetween two friction ridge impressions to effect adecision, i.e., made by the same friction skin, not madeby the same friction skin, or insufficient detail to form aconclusive decision.
•• VerificationVerification – an independent analysis, comparisonand evaluation by a second qualified examiner of thefriction ridge impressions.
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