Professor Mike WieheProfessor Mike Wiehe

Fingerprint Processing and Fingerprint Processing and PhotographyPhotography

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GoalsGoals

Students will receive a brief Students will receive a brief background about latent printsbackground about latent prints

Traditional latent print recovery Traditional latent print recovery techniques will be discussedtechniques will be discussed

Students will learn about new Students will learn about new chemical processes utilized todaychemical processes utilized today

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A fingerprint is the impression made by the A fingerprint is the impression made by the papillary ridges on the ends of the fingers papillary ridges on the ends of the fingers and thumbs. Fingerprints afford an infallible and thumbs. Fingerprints afford an infallible means of personal identification, because means of personal identification, because the ridge arrangement on every finger the ridge arrangement on every finger of every human being is unique and of every human being is unique and does not alter with growth or agedoes not alter with growth or age. .

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RidgesRidges Each ridge of the epidermis (outer skin) is dotted Each ridge of the epidermis (outer skin) is dotted

with sweat pores for its entire length and is with sweat pores for its entire length and is anchored to the dermis (inner skin) by a double anchored to the dermis (inner skin) by a double row of peglike protuberances, or papillae. row of peglike protuberances, or papillae.

InjuriesInjuries such as superficial burns, abrasions, or such as superficial burns, abrasions, or cuts cuts do not affect the ridge structuredo not affect the ridge structure or alter or alter the dermal papillae, the dermal papillae, and the original pattern is and the original pattern is duplicated in any new skin that growsduplicated in any new skin that grows..

An injury that destroys the dermal papillae, An injury that destroys the dermal papillae, however, will permanently obliterate the ridges. however, will permanently obliterate the ridges.

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Latent FingerprintingLatent Fingerprinting

Involves locating, preserving, and identifying Involves locating, preserving, and identifying impressions left by a culprit in the course of impressions left by a culprit in the course of committing a crime. committing a crime.

In latent fingerprints, the ridge structure is In latent fingerprints, the ridge structure is reproduced not in ink on a card but on an object reproduced not in ink on a card but on an object in sweat, oily secretions, or other substances in sweat, oily secretions, or other substances naturally present on the offender's fingers. naturally present on the offender's fingers.

Most latent prints are colorless and must Most latent prints are colorless and must therefore be "developed," or made visible, before therefore be "developed," or made visible, before they can be preserved and compared. they can be preserved and compared.

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Latent FingerprintingLatent Fingerprinting

This is done by brushing them with various This is done by brushing them with various powders containing chalk or lampblack combined powders containing chalk or lampblack combined with other agents. with other agents.

The latent impressions are preserved as evidence The latent impressions are preserved as evidence either by photography or by lifting powdered either by photography or by lifting powdered prints on the adhesive surfaces of tape.prints on the adhesive surfaces of tape.

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Three Kinds of Crime Scene Three Kinds of Crime Scene PrintsPrints

LATENT PRINT (hidden print) is a misnomer but often LATENT PRINT (hidden print) is a misnomer but often used inclusively. There are actually three kinds of used inclusively. There are actually three kinds of crime scene prints. These are:crime scene prints. These are: 1. VISIBLE PRINTS which are prints made by fingers touching 1. VISIBLE PRINTS which are prints made by fingers touching

a surface after the ridges have been in contact with a a surface after the ridges have been in contact with a colored material such as blood, paint, grease, or ink.colored material such as blood, paint, grease, or ink.

2. PLASTIC PRINTS which are ridge impressions left on a soft 2. PLASTIC PRINTS which are ridge impressions left on a soft material such as putty, wax, soap, or dust.material such as putty, wax, soap, or dust.

3. True LATENT PRINTS which are invisible print impressions 3. True LATENT PRINTS which are invisible print impressions caused by the perspiration on the ridges of one’s skin caused by the perspiration on the ridges of one’s skin coming in contact with a surface and making an invisible coming in contact with a surface and making an invisible impression on it. Perspiration contains water, salt, amino impression on it. Perspiration contains water, salt, amino acids, or oils and easily allows impressions to be made.acids, or oils and easily allows impressions to be made.

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Conditions Affecting The Conditions Affecting The Quality Quality

Of Latent Prints Of Latent Prints The surface on which the print is depositedThe surface on which the print is deposited The nature of the material contaminating the The nature of the material contaminating the

fingerprintfingerprint Any physical or occupational defects of the Any physical or occupational defects of the

person making the printperson making the print How the object on which the prints appear was How the object on which the prints appear was

handledhandled The amount of the contaminationThe amount of the contamination

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Methods Of Developing Methods Of Developing Latent PrintsLatent Prints

Traditional powdersTraditional powders Fluorescent PowdersFluorescent Powders ChemicalsChemicals Cyanoacrylate of superglue fumingCyanoacrylate of superglue fuming Visualization under:Visualization under:

LaserLaser Alternative lightAlternative light Ultraviolet illuminationUltraviolet illumination

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• Visual Examination All

• Powders Smooth

• Ninhydrin Paper, Cardboard, Wood etc

• Sticky-Side Powders Adhesive Tapes

• Physical Developer Wet paper

• Fluorescence Various

• Superglue + Fluorescence Polythene, Plastic molding, etc

• Amido Black Fingerprints in Blood

• Acid Yellow Fingerprints in Blood

Most Effective Techniques for the Detection of Fingerprints

Surfaces

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Typical Exhibits from Crime ScenesTypical Exhibits from Crime Scenes

For each surface there is usually one most productive technique which can be used

on less important cases to save time

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Superglue + Basic Yellow 40Sudan Black

Gentian Violet

Ninhydrin

Amido BlackSmall Particle Reagent

Typical Exhibits from Crime ScenesTypical Exhibits from Crime Scenes

For each surface there is usually one most productive technique which can be used

on less important cases to save time

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Powders - Can be effective on some Powders - Can be effective on some surfaces but must use best powderssurfaces but must use best powders

Synthetic fibre, Synthetic fibre, animal hair and animal hair and glass fibre glass fibre brushes in usebrushes in use

Hundreds of Hundreds of types of types of powder powder availableavailable

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Home Office Test Programme Assessment of the Assessment of the

effectiveness of effectiveness of different powders different powders and brushes on and brushes on typical surfacetypical surface

Using 20 to 30 donors and Using 20 to 30 donors and investigating performance on investigating performance on different types of surface over different types of surface over varying periods of timevarying periods of time

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NinhydrinNinhydrin

It was not until the mid 1950's that it was discovered that It was not until the mid 1950's that it was discovered that ninhydrin could be used to develop latent prints on porous ninhydrin could be used to develop latent prints on porous surfaces. surfaces.

When ninhydrin comes into contact withamino acids in When ninhydrin comes into contact withamino acids in

fingerprint residue, the reaction yields a red to purple print.fingerprint residue, the reaction yields a red to purple print.

Effective on virtually any porous surface, ninhyrdin is most Effective on virtually any porous surface, ninhyrdin is most appropriate for paper.appropriate for paper.

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NinhydrinNinhydrin

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Ninhydrin Used On Bloody Shoe Ninhydrin Used On Bloody Shoe PrintPrint

BEFOREBEFORE AFTERAFTER

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Use of Amino Acid Reagents at Use of Amino Acid Reagents at Crime Scenes on WallpaperCrime Scenes on Wallpaper

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Amido BlackAmido Black

Aqueous Amido Black is a protein dye solution Aqueous Amido Black is a protein dye solution sensitive to the protiens in blood and other sensitive to the protiens in blood and other substances.substances.

It will not react with the typical proteins found in It will not react with the typical proteins found in latent prints.latent prints.

Applied to non-porous materials such as plastic, Applied to non-porous materials such as plastic, glass or metal.glass or metal.

It is a corrosive chemical, recommended to do It is a corrosive chemical, recommended to do presumptive blood test and DNA collection prior presumptive blood test and DNA collection prior to applicationto application

Photographs easily on light surfaces, utilize a Photographs easily on light surfaces, utilize a forensic light source if located on a dark surface.forensic light source if located on a dark surface.

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Amido BlackAmido Black

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Acid Yellow 7Acid Yellow 7

Acid Yellow 7 stain is one of the newer and more Acid Yellow 7 stain is one of the newer and more effective fluorescent stains used to enhance bloody effective fluorescent stains used to enhance bloody footwear and fingerprint impressions on nonporous footwear and fingerprint impressions on nonporous surfaces. surfaces.

Staining reveals a yellowish colored print which Staining reveals a yellowish colored print which fluoresces under blue-green light (400-490 nm). fluoresces under blue-green light (400-490 nm).

When lifted with a white gelatin lifter the When lifted with a white gelatin lifter the impression will often reveal enhanced fluorescence.impression will often reveal enhanced fluorescence.

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Acid Yellow 7 Bloody Fingerprint on Glass Bottle

Fingerprints in BloodFingerprints in Blood

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Superglue Chamber for Fingerprints on Plastics

The fingerprint deposit initiates the growth of fibrous deposit from ethyl cyanoacrylate vapor under conditions of high humidity; this is visible as a white deposit which may be enhanced with fluorescent dyes

Enhanced with fluorescent dyes

Treatment Chamber

Developed Fingerprint

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Making Fingerprints Fluoresce

Chemically developed prints can sometimes be difficult to see and photograph

A number of fluorescent reagents have been developed for the visualisation of fingerprints

Some dyes may be used to enhance chemically developed fingerprints

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High Intensity Light Sources

Crimescopes and Lumalites Crimescopes and Lumalites use very similar or identical use very similar or identical arc lamps to locate latent arc lamps to locate latent printsprints

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A Solid State 532 nm Laser in Use

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Alternate Light Source Accessories

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Iodine FumingIodine Fuming

Iodine crystals give off vapors that adsorb Iodine crystals give off vapors that adsorb physically to the oil and fat substances of a physically to the oil and fat substances of a fingerprintfingerprint

Use on porous and non-porous surfaces with fresh Use on porous and non-porous surfaces with fresh printsprints

Developed prints are not fixed and need to be Developed prints are not fixed and need to be documenteddocumented

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Physical DeveloperPhysical Developer

Physical developer is a reagent that reacts Physical developer is a reagent that reacts with the lipids, fats, and oils, which are with the lipids, fats, and oils, which are present in fingerprint residuespresent in fingerprint residues

Typically used after Ninhyrdrin and the Typically used after Ninhyrdrin and the forensic light sourceforensic light source

Photograph after each stepPhotograph after each step

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Latent fingerprint on paper initiates deposition of silver from a surfactant stabilised silver nitrate solution

Will even detect fingerprints on paper soaked in water for weeks

Specific Reaction - Catalysis/InitiationSpecific Reaction - Catalysis/InitiationFingerprint Deposits Developed with ‘Physical Developer’Fingerprint Deposits Developed with ‘Physical Developer’

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Physical Developer ProcessingPhysical Developer Processing

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Small Particle ReagentSmall Particle Reagent

It is a physical development technique where It is a physical development technique where small black particles adhere to the fatty small black particles adhere to the fatty substances left in fingerprint residuesubstances left in fingerprint residue

Most well known for its ability to develop latent Most well known for its ability to develop latent prints on wet surfaces, such as vehicles wet with prints on wet surfaces, such as vehicles wet with rain rain

Can spray it on a surface or dip an object in itCan spray it on a surface or dip an object in it

Photograph any latent prints then dried prints can Photograph any latent prints then dried prints can be lifted using traditional methodsbe lifted using traditional methods

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Small Particle ReagentSmall Particle Reagent

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Sequential ProcessingSequential Processing• There is a large variation in the chemical

constituents of fingerprints from different

people• There is also a large variation in the

amount of latent fingerprint deposit

between different people• The deposit from the same person also

varies from day to day and hour to hour• Using one technique after another can

therefore produce additional fingerprints• The processes must be used in the

correct sequence• Different surfaces require different

sequences of process

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• Different types of surface Different types of surface

require different treatment require different treatment

sequencessequences• Use of one process after Use of one process after

another can double numbers another can double numbers

of developed fingerprintsof developed fingerprints

Sequential ProcessingSequential Processing

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Typical Police Fingerprint LaboratoryTypical Police Fingerprint Laboratory