2Summary What are fingerprints? How are fingerprints analyzed? How are fingerprints collected?
3What are fingerprints? Friction ridge skin pattern Found on fingers, palms, toes, soles of feet.Composed of ridges (hills) and furrows (valleys)Black = RidgesWhite = Valleys
4What are fingerprints? Develop in early embryonic development. Pattern based on genetics, detail somewhat randomIdentical twins do not have identical fingerprints
5Categorized by pattern and minutiae FingerprintsHow are fingerprints analyzed?Categorized by pattern and minutiae
6How are fingerprints analyzed? PatternsArchLoopWhorl
7How are fingerprints analyzed? MinutiaeBifurcationRidge EndingDotIsland
8Computer software compares the location of these minutiae. FingerprintsComputer software compares the location of these minutiae.
9History of Fingerprints Long history of fingerprints as signatureCriminal identification first done by a system of body measurements called anthropometry.Bertillon’s anthropometry system used 11 body measurements to identify an individual
10History of Fingerprints Henry invented a system for classifying fingerprints.Allowed fingerprint records to be searched.Based on all 10 prints, so matching one print would be difficult.
12Modern Fingerprint Analysis FingerprintsModern Fingerprint AnalysisComputer system stores patterns and minutiae of printsAFIS: automated fingerprint identification system
13There are 3 types of fingerprints Visible – left by dirt, grease, blood, etc.Does not need processing
14There are 3 types of fingerprints Impression – indentation in soft material (butter, putty, tar, etc.)Does not need processing
15There are 3 types of fingerprints Latent – requires processing to make visible and suitable for analysis
16What are the invisible components? Fingerprints > AnalysisWhat are the invisible components?Multiple sweat glands secrete onto fingers, palms, etc.Sweat contains:Inorganic ions (Na+, Cl -)Proteins, amino acidsLipidsOther
17Development and Collection: Fingerprints > AnalysisDevelopment and Collection:Scene or Lab?No rule: Depends on situationFingerprint must be photographed after development (scene or lab)
18Physical Development: Dusting Fingerprints > AnalysisPhysical Development: DustingApply powder to latent print or area.Powder adheres to print.Brush and Powder
19Physical Development: Dusting Fingerprints > AnalysisPhysical Development: DustingApply powder to latent print or area.Powder adheres to print.Magnetic Brushand Powder
20Chemical Development: Fingerprints > AnalysisChemical Development:Silver NitrateNo longer used (messy, not sensitive)Silver reacts with Cl - ions in print
21Chemical Development: Fingerprints > AnalysisChemical Development:Iodine FumingIodine sublimes (solid → gas)Iodine reacts with lipid components; becomes trapped in the print.Fuming wand or chamberDirty Brown Color
22Chemical Development: Fingerprints > AnalysisChemical Development:NinhydrinReacts with amino acids; purple colorPainted or sprayed on areaHeated to react
23Chemical Development: Fingerprints > AnalysisChemical Development:Super glue fumingFumes with heat or base (NaOH)Fumed in cabinetsOff-white print
24Chemical Development: Fingerprints > AnalysisChemical Development:Ninhydrin and super glue prints can be further processed:DustedChemically treated to fluoresce (using laser or alternative light)
25Collection of prints: Tape lift: Tape placed over developed print Fingerprints > CollectionCollection of prints:Tape lift:Tape placed over developed printTape then placed on white card.
26Fingerprints > Collection Collection of prints:Sometimes a photograph will be the only permanent record.