1/10/2018. Chapter 6 Fingerprints By the end of this chapter you will be able to:

Transcription

1 Frensic Science: Fundamentals & Investigatins, e Cengage/NGL/Suth-Western 06 Fingerprints By the end f this chapter yu will be able t: 6. Outline the histry f fingerprinting. 6. Describe the characteristics f fingerprints. 6.3 Cmpare and cntrast the basic types f fingerprints. 6.4 Describe hw criminals attempt t alter their fingerprints. 6.5 Present and refute arguments that questin fingerprint evidence reliability. Frensic Science: Fundamentals & Investigatins, e Cengage/NGL/Suth-Western 06 Fingerprints By the end f this chapter yu will be able t: 6.6 Summarize the prper prcedures fr cllecting fingerprint evidence. 6.7 Describe the latest identificatin technlgies. 6. Determine if a fingerprint is cnsistent with a fingerprint n recrd. 6.9 Lift a latent print. 6.0 Prepare a ten card and analyze the ridge patterns f the prints. 3 Frensic Science: Fundamentals & Investigatins, e Cengage/NGL/Suth-Western 06

2 Vcabulary 4 arch cre delta fingerprint IAFIS (Integrated Autmated Fingerprint Identificatin System) latent fingerprint lp Frensic Science: Fundamentals & Investigatins, e minutiae patent fingerprint plastic fingerprint ridge cunt ridge pattern ten card whrl Cengage/NGL/Suth-Western 06 5 Intrductin Pudd nhead Wilsn was published in 94. Lawyer wh used fingerprints t prve his clients were inncent. Pudd nhead Wilsn states that a suspect s fingerprints are: his signature, his physilgical autgraph, s t speak, and this autgraph cannt be cunterfeited, nr can he disguise it r hide it away, nr can it becme illegible by the wear and mutatins f time. Frensic Science: Fundamentals & Investigatins, e Cengage/NGL/Suth-Western 06 Histry 6 Ancient cultures used fingerprints as persnal markings BCE Fingerprints were pressed int clay tablet cntracts in Babyln and China. 64 Dr. Nehemiah Grew described the patterns he saw n human hands under a micrscpe. 7 Jhann Christph Andreas Mayer described that fingerprints are unique t each individual. Prbably first t recgnize this. 3 Jan Evangelist Purkyn described nine distinct fingerprint patterns. Frensic Science: Fundamentals & Investigatins, e Cengage/NGL/Suth-Western 06

3 7 Frensic Science: Fundamentals & Investigatins, e Cengage/NGL/Suth-Western 06 Histry (cntinued) 56 Sir William Herschel began cllecting fingerprints. 79 Alphnse Bertilln created a way t identify criminals that were repeat ffenders. Sir Francis Galtn verified that fingerprints d nt change with age. 96 Sir Edmund Richard Henry (and clleagues) created a system that divided fingerprint recrds int grups. Their wrk was the basis f the ten card. Frensic Science: Fundamentals & Investigatins, e Cengage/NGL/Suth-Western 06 9 Frensic Science: Fundamentals & Investigatins, e Cengage/NGL/Suth-Western 06 3

4 Histry (cntinued) 0 The FBI-maintained IAFIS had mre than 76 millin cmputerized fingerprints, mugshts, scars, tatt phts, and ther identificatin recrds. The system will sn be enhanced by Advanced Fingerprint Identificatin Technlgy (AFIT). 03 The FBI was integrating the ability t cmpare crime-scene palm prints with prints cllected at the time f arrest. Abut 0-30% f latent prints at a crime scene cme frm the palm r side f the hand frm the little finger t the wrist. 0 Frensic Science: Fundamentals & Investigatins, e Cengage/NGL/Suth-Western 06 Frensic Science: Fundamentals & Investigatins, e Cengage/NGL/Suth-Western 06 What Are Fingerprints? Fingerprints arise frm dermal papillae, the layer f cells between uter skin (epidermis) and inner skin (dermis) Frictin ridges start t at -0 weeks f gestatin and becme fully develped by seventeenth week Pattern cannt be altered easily prtected by epidermis Frictin ridges are series f hills (ridges) and valleys (furrws) n the skin f the hands and feet Frensic Science: Fundamentals & Investigatins, e Cengage/NGL/Suth-Western 06 4

5 Develpment f Fingerprints As frictin ridges develp, perspiratin glands are frmed and cnnect t pres in the epidermis Pres release waste materials such as sweat, ils, prteins, fats and ther materials When finger tuches surface, these wastes are depsited, frming a fingerprint pattern that matches the frictin ridge pattern f the individual frictin ridges shwing pres emitting sweat Frensic Science: Fundamentals & Investigatins, e 3 Cengage/NGL/Suth-Western 06 Characteristics f Fingerprints 4 Frensic Science: Fundamentals & Investigatins, e Cengage/NGL/Suth-Western 06 Arches, Lps, Whrls Categrized by the presence r absence f a delta (triangular intersectin f ridges) An Arch has NO deltas A Lp has ONE delta A Whrl has TWO deltas Frensic Science: Fundamentals & Investigatins, e Arch Lp 5 Cengage/NGL/Suth-Western 06 Whrl 5

6 Arches Arch patterns differ in severity f slpe f arch Tw types f patterns: Plain Arch, Tented Arch 5% f fingerprints Plain Arch Tented Arch Frensic Science: Fundamentals & Investigatins, e 6 Cengage/NGL/Suth-Western 06 7 Frensic Science: Fundamentals & Investigatins, e Cengage/NGL/Suth-Western 06 Lps Cre Delta Lp ridges enter frm either side f the finger, re-curve and pass back alng the side frm which they entered Lps are identified by the directin lp pens t knwn as radial (thumb side) r ulnar (little finger side) Nearly 65% f prints are lps Ulnar Lp Radial Lp Frensic Science: Fundamentals & Investigatins, e Cengage/NGL/Suth-Western 06 6

7 Characteristics f Fingerprints (cntinued) 9 Frensic Science: Fundamentals & Investigatins, e Cengage/NGL/Suth-Western 06 Whrls Whrls: many circular ridges are cmmn Fur types f whrls Plain Duble lp Central pcket lp Accidental Make up abut 30% f fingerprints Frensic Science: Fundamentals & Investigatins, e 0 Cengage/NGL/Suth-Western 06 Whrls Plain Whrl is lcated between tw deltas f the whrl pattern and has a minimum f ne ridge that is cntinuus arund the pattern Central Pcket Lp Whrl is nt lcated between tw deltas f the whrl pattern and has a minimum f ne ridge that is cntinuus arund the pattern Duble Lp Whrl is made up f tw lps that swirl arund each ther Accidental Whrl is a pattern that cmbines tw r mre patterns, excluding the plain arch, and/r des nt clearly meet the criteria fr any f the ther patterns Frensic Science: Fundamentals & Investigatins, e Cengage/NGL/Suth-Western 06 7

8 Characteristics f Fingerprints (cntinued) Frensic Science: Fundamentals & Investigatins, e Cengage/NGL/Suth-Western 06 Types f Ridge Characteristics r Minutiae Bifurcatins - ridges split int tw ridges Ending ridge - simple straight ridge Dt - tiny rund ridges Shrt ridge - small islated segment f ridge Enclsure - ridge that frms frks, then a cmplete circle, then becmes single ridge again Trifurcatin - ridge that splits int three ridges Frensic Science: Fundamentals & Investigatins, e 3 Cengage/NGL/Suth-Western 06 Ridge Characteristics r Minutiae a. Bifurcatin b. Dt c. Enclsure d. Ending ridge e. Shrt ridge 3rd Frensic Editin, Science: 06, Fundamentals CRC & Investigatins, e Press, Jay A. Siegel and Kathy Mirakvits 4 Cengage/NGL/Suth-Western 06

9 5 Frensic Science: Fundamentals & Investigatins, e Cengage/NGL/Suth-Western 06 Types f Fingerprints Fund at Crime Scenes Patent prints: prints easily seen such as left by bld, grease, dirt, r fresh paint Plastic prints: fund as impressins n wax, clay, r butter Latent prints: invisible t the naked eye Patent Fingerprints: Fingerprints in Bld Plastic Fingerprints: Fingerprints in Sft Putty Frensic Science: Fundamentals & Investigatins, e 6 Cengage/NGL/Suth-Western 06 Detectin and Visualizatin f Fingerprints Patent and plastic prints are generally easy t discver Majr challenge lies in attempting t recver latent prints frm crime scene Different surfaces present different challenges Lcating and visualizing prints can be dne: Reflected Ultravilet Imaging System Pwder dusting regular pwder and magnetic Chemical enhancement methds Frensic Science: Fundamentals & Investigatins, e 7 Cengage/NGL/Suth-Western 06 9

10 Chemical Methds f Fingerprint Visualizatin Idine fuming ldest chemical methd idine crystals sublimate t idine gas gas adheres t fats in the fingerprint residue Silver Nitrate reacts with ins in the sweat residue Ninhydrin mst ppular used fr develping n prus surfaces reacts with amin acids t frm a clred cmpund knwn as Ruhemann s Purple Cyanacrylate (superglue fuming) reacts with amin acids, prteins, and fatty acid residues Frensic Science: Fundamentals & Investigatins, e Cengage/NGL/Suth-Western 06 Flurescence f Fingerprints Fingerprint residues cntain substances that will fluresce when expsed t certain wavelengths f light Argn-in lasers have been used After cyanacrylate fuming is dne, Rhdamine 6G, which is a dye, was applied. This fluresces and emits yellw light Argn laser aimed at print and pht is taken using a special filter Frensic Science: Fundamentals & Investigatins, e 9 Cengage/NGL/Suth-Western 06 Cmparisn f Prints Crime scene prints cmpared t knwn prints Ten print card: used t cllect fingerprints Rlled print: fingerprint rlled frm cuticle t cuticle Tap prints: fingerprints that are tapped in ink and then placed at bttm f ten print card Frensic Science: Fundamentals & Investigatins, e 30 Cengage/NGL/Suth-Western 06 0

11 Digital Fingerprinting Live Scan: 990 s replaces inked ten print card captures frictin ridge image and stres digitally in cmputer database Frensic Science: Fundamentals & Investigatins, e 3 Cengage/NGL/Suth-Western 06 Classificatin f Sets f Fingerprints Tw types f fingerprint cmparisns First is t identify a particular persn frm his r her fingerprints Prints are taken and sent t database (such as ne FBI maintains) classificatin system Henry system uses several methds t classify prints, each based n a different set f characteristics. One methd is classifying fingerprints based n whrls. Frensic Science: Fundamentals & Investigatins, e 3 Cengage/NGL/Suth-Western 06 The Henry Classificatin System L L A W A A W L L L ) R Thumb 6 6) L Thumb 4 ) R Index 6 7) L Index 3) R Middle ) L Middle 4) R Ring 9) L Ring 5) R Little 4 0) L Little The sum f the values f the white squares that cntain a Whrl (plus ne) is the numeratr f the primary classificatin. The sum f the values f the dark squares that cntain a Whrl (plus ne) is the denminatr f the primary classificatin. ) R Thumb ) R Index 3) R Middle 4) R Ring 6) L Thumb 7) L Index ) L Middle 9) L Ring 5) R Little 0) L Little = Frensic Science: Fundamentals & Investigatins, e Cengage/NGL/Suth-Western 33 06

12 Henry System Value Chart Left Hand 4 6 Right Hand Black numbers = Finger number Blue numbers = Finger value (if it is a whrl) (even_finger_values_fr_whrls) Henry_Classificatin_Frmula (dd_finger_values_fr_whrls) Frensic Science: Fundamentals & Investigatins, e Cengage/NGL/Suth-Western Internatinal Assciatin fr Identificatin Umbrella grup f fingerprint experts Decided in 990 n standard minimum number f pints wuld be necessary fr psitive identificatin Three level f frictin ridge details wuld be used t identify prints Frensic Science: Fundamentals & Investigatins, e 35 Cengage/NGL/Suth-Western 06 Levels f Frictin Ridge Details Level general features and patterns can be used t exclude a print nly Level includes particular ridges (minutiae) in same place that allw individualizatin f an unknwn print Level 3 requires lw pwer micrscpe identifies minute imperfectins, such as scars, edge shapes, sweat gland pres s unique their presence virtually assures individuality Frensic Science: Fundamentals & Investigatins, e 36 Cengage/NGL/Suth-Western 06

13 Autmated Fingerprint Identificatin Systems (AFIS and IAFIS) Allw fr autmated search prcess f fingerprints Vast sets f ten print cards made it almst impssible t search fr prints FBI, Natinal Institute fr Standards and Technlgy (NIST) and Natinal Crime Infrmatin Center develped standard frmat fr fingerprint data Revised in 999 by FBI thrugh IAFIS Frensic Science: Fundamentals & Investigatins, e 37 Cengage/NGL/Suth-Western 06 AFIS-Autmated Fingerprint Identificatin System Operates by anchring psitin f fingerprint and searching database Uses tw types f ridges: Bifurcatins Ridge endings Database wrks by querying prints t find nes with same number f ridges in relative psitins Mst likely matches are displayed fr cmparisn by a fingerprint examiner 3 Frensic Science: Fundamentals & Investigatins, e Cengage/NGL/Suth-Western 06 IAFIS Integrated Autmated Fingerprint Identificatin System Entirely digital system Cmpares a persn s set f ten fingerprints against a database f millins f prints in a few minutes Prblems f incmpatibility f frmats is being slved by develpment f wrkstatins that generate input directly int system Frensic Science: Fundamentals & Investigatins, e 39 Cengage/NGL/Suth-Western 06 3

14 Can yu alter yur fingerprints? In mst cases, the act f alteratin will make the fingerprints easier t ID by adding cuts/scars t the ridge structure Example: Jhn Dillinger (930 s) put acid n his fingers, but did nt destry his ridges cmpletely Recently Mythbusters did a segment n making casts f fingerprints and verlaying them Frensic Science: Fundamentals & Investigatins, e 40 Cengage/NGL/Suth-Western 06 The Future f Fingerprinting Fingerprints can be scanned at a reslutin f 500 t 000 dts per inch. Nanparticles have been added t fingerprint pwders making pr patterns appear even sharper. The materials that we tuch leaves trace evidence n ur fingers and hands, which is in turn is left behind n the bjects we tuch. 4 Frensic Science: Fundamentals & Investigatins, e Cengage/NGL/Suth-Western 06 4 Frensic Science: Fundamentals & Investigatins, e Cengage/NGL/Suth-Western 06 4

15 Summary Humans have nticed the patterns n their hands fr thusands f years, but it was nt until 64 that these patterns were described in detail. In the mid-00s, the idea f a fingerprint s uniqueness was studied, and the applicatin f fingerprints t an identificatin system began. By the late 00s, tw effective systems were being used t identify criminals, and fingerprints were being cllected as evidence in crimes. The elevated regins in a fingerprint are called frictin ridges. Fingerprints cnsist f several main ridge patterns, including whrls, lps, and arches. They have a cre, which is an area where ridges separate r unite after running in a parallel directin. The triangular regin lcated near a lp pattern, r whrl, is called a delta. Fingerprints are frmed in the wmb at abut week 0 f gestatin. They are frmed between tw layers f skin, and their shape des nt change during a persn s lifetime. They are unique t an individual. Nt even identical twins have identical fingerprints. 43 Frensic Science: Fundamentals & Investigatins, e Cengage/NGL/Suth-Western 06 Summary (cntinued) Fingerprints left n an bject are created by the naturally ccurring ridges in the skin f fingertips and secretins frm sweat glands that leave small amunts f ils and salts when the ridges are pressed against an bject. The residues leave an impressin f the ridges fund n the finger f the dnr. The basic types f fingerprints are patent (visible) fingerprints, plastic (indentatin) fingerprints, and latent (nt visible t the unaided eye) fingerprints. They are characterized as lps, whrls, r arches, and are cmpared n the basis f their minutiae. Criminals have sught t alter their fingerprints with chemicals, surgery, and superficial destructin. Sme fingerprints can temprarily be altered by lng-term cntact with rugh surfaces. Attempts at permanent fingerprint alteratin have nt been successful. 44 Frensic Science: Fundamentals & Investigatins, e Cengage/NGL/Suth-Western 06 Summary (cntinued) 45 Mistakes in fingerprint analysis have led t wrngful cnvictins, mstly because f human errr. New frensic standards are being develped thrugh the Scientific Wrking Grups and the Organizatin f Scientific Area Cmmittees. The Integrated Autmated Fingerprint Identificatin System (IAFIS) is a natinal database that hlds mre than 76 millin fingerprint, identifying mark, and criminal histry recrds. Fingerprints can be cllected frm surfaces by dusting them with certain pwders and impressing them n tape, r putting them int cntact with certain chemicals that help reveal the fingerprints. Frensic Science: Fundamentals & Investigatins, e Cengage/NGL/Suth-Western 06 5