Technology Transition Workshop| Brian Dalrymple Forensic Light

TechnologyTransition Workshop

The Forensic Light Source –History, Evolution,Extension & Acquisition

Technology Transition Workshop| Brian Dalrymple


Latent Fingerprint Image Enhancement: The Forensic Light Source – History, Evolution, Extension & Acquisition 2



Latent Fingerprint Image Enhancement: The Forensic Light Source – History, Evolution, Extension & Acquisition

History

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Serendipity 1976Ninhydrin on black cardboardIodine?J.M. DuffIodine fluorescence in 1911Robert Olsen, Sr.Inherent fluorescence?

History

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E.R. Menzel – Argon ion laserTLC plates – fingerprint fluorescenceLaser safety gogglesInherent fluorescence on black tapeRevealed and photographed by laserIdentified as suspectFirst case in history• Laser application• Fluorescence as serious tool

History

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1977 – Argon Ion Laser

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1977 – Argon Ion Laser

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Laser Implications

No previous light exploitation UV fluorescent powder ineffectiveNew direction in fingerprint detection% absorption/reflectionNothing absorbs 100% of incident lightNothing reflects 100% of incident light Fixed dynamic rangeFingerprints – sub‐nanogramLimited detection sensitivity

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Luminescence

0% reflected incident lightLuminescence of fingerprintLuminescence of substrateMuch wider potential dynamic rangeMuch more sensitive

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1976 – Argon Laser

Fingerprints on skinFeasibility study – detection on skinFingerprint photographed on living skinDetected and photographed Immediately after deposition

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Fingerprints on SkinSuppositions

Body begins decay at deathFingerprint on skin extremely fragileVulnerable to:• Time• Temperature • HumidityNot feasible on living skinSmooth hairless skin

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Older manHigh heat, high humidityUntreated fingerprint on handShaking handsFingerprint classifiable Almost certainly contamination

Visitor to OPP Lab

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Argon Laser – 1977

80 fraud chequesExamined by laser4 impressions locatedOne identified as suspectTreated with ninhydrin60 impressions developedSeveral suspects identifiedNot the one revealed by laser

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Evolution

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Circa 1980

Introduction of YAG laserPortableDurable110 V532nm emissionPulse laserLow repetition rateDiscontinued

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1991 – 1992 Serial Killer

Suspect’s home discoveredHome examined by LumiliteTraces of ridge detail detected

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1991 – 1992 Serial Killer

Residence examined by argon laser40 untreated impressions located

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1990’s

Re‐introduction of YAG laserPortableDurable110 V532nm emissionMuch better pulse rateCoherent speckle

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Results – Laser Alone1977 – 1995

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Paper napkin found beside bodyOnly physical evidenceLaser examinationOne impression locatedIdentified as accusedNot detected by ninhydrin

Homicide

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Valerian Trifa – 1984

Subject accused of war crimesGerman archival documentsExamined by laserImpression on postcard• Identified as subject• Recipient Heinrich Himmler• Print 42 years old

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Fish Knife

Varnished wooden handleExamined by powder – negativeExamined by laser – impression foundIdentified as suspect

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Failed to detonateBlack electric tapeFingerprint detected by laserIdentified as accused

Improvised Explosive Device

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Alternatives

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1976 – 1979

No “alternatives” on horizonAll results inherent fluorescenceNo chemical extensionsMenzel – circa 1980 – CA/R6GCombo greater than the sum of partsSingle biggest advance of last 20 years

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Circa 1979 – 1980

Appearance of first laser “alternatives”• Lumilite (Canada)• Polilight® (Australia)• Omnichrome (US)Primarily for CA/R6GNo documented reporting of untreated fingerprint detection

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Polilight® PL‐500

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Polilight® PL‐500

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Alternate Light Sources

Much cheaper than lasersMuch safer than lasers for eyesCheaper to runAir‐cooledPortableRelatively low maintenance

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Circa 1985

Menzel – zinc chloride Post ninhydrin treatmentAlmog et al. – ninhydrin analogs 5 methylthion ninhydrin5 methoxi‐ninhydrin and othersAll with fluorescent properties

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Focus Now on DevelopingFluorescing Reagents

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Circa 1990

C.A. Pounds – DFOFluorescing fingerprint reagentExcited by argon laser or “ALS”Ninhydrin post‐DFO reveals more detail Perceived value of laser diminished

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Circa 2000

J. Almog, Israel Police ForceIndanedione Ninhydrin analogFluorescing fingerprint reagentExcited by argon laser or “ALS”

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Circa 2000

Introduction of LED lightsCheaperCool, efficientRobustVery portableSpectral output similar to lamps

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Circa 2006 – Semiconductor Laser

Introduction of Coherent® TracER™Optical pumped semiconductor laser110 V powerBattery option – 2 hours of cord‐free useCool, efficientRobustVery portableOutput wavelength can be engineeredCurrent version is 532nmNo coherent speckle

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Semiconductor Laser

OPSC – Optically Pumped SemiconductorLasing medium is semiconductor chipOutput wavelength can be engineeredCurrent version – 532nm

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Photographs courtesy of Coherent Inc.

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Pig Farm

Serial killerOver 25 victimsFarm examined by laser and FLSPalm print detected by FLSIdentified as victimNot detected by laser

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Filtered Lamps

1980 to presentLumilite – CanadaPolilight®OmnichromeSpex CrimeScope®

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Cheaper!Lighter!

More portable!More dependable!

No speckle!

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Questions?

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Contact Information

Brian Dalrymple

PO Box 296, Orillia ON L3V 6J6

Canada

Tel. 705‐835‐0227

[email protected]

Note: All images are courtesy of Brian Dalrymple unless otherwise noted.

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Technology Transition Workshop| Brian Dalrymple Forensic Light

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