Forensic Aspects of Evidence

Fingerprint Identification

“Lifted” from Steve Gilbert, M.F.S., Ph.D.

History of Fingerprints

• 1684 – Nehemiah Grew reported that various patterns were present in the fingers

• 1685 – Bidloo produced first fingerprint drawing• 1823 – Johannus Purkinje wrote a commentary of

the skin system• 1880 – Henry Faulds stated that chance prints at

scenes could identify perpetrator (Faulds)

History of Fingerprints

• 1892 – Francis Galton wrote his book called “Fingerprints”. Studied over 40,000 prints and failed to find any matches

• 1901 – Sir Edward Henry established the first and continuing classification system

• 1902 – New York began collecting fingerprints of job applicants

History of Fingerprints

• 1903 – West Brothers case in Kansas• 1904 – First fingerprint bureau• 1905 – US Army began fingerprinting soldiers• 1924 – FBI established FP system

Parts of the Hand

Proximal

Distal

UlnarRadial

Bracelet Crease

Proximal Traverse Crease

Thenar Eminence

I

II IIIIV

Inter Digital Pads I - IV

Hypo Thenar Eminence

Meta Carpal Crease

Distal Traverse Crease

Inter Digital Intervals

Embryology

• 6 weeks: pads II, III, IV• 8 weeks: finger elongate, separate• 8-12 weeks: pads round, separate pads• 13 weeks: pads regress smaller• 3-4 months: ridges form• The number ridges dictated by fullness of finger

pad

Pattern Anomalies

• Dissociation of Ridges – no ridges• Dysplasia – Faulty development of friction skin• Cuspal Patterns – ridges run distal to proximal

rather than side to side

Loops

One or more ridges enter on either side, recurve, touch or pass an imaginary line drawn from the delta to core, and terminate or tend to terminate on or toward the same side the ridge or ridges entered.

Loops opening towards the little finger is the ulnar loop, whereas the loop opening towards the thumb is the radial loop.

Ridge Counting

The number of ridges intervening between the delta and the core is known as the ridge count. (yellow tick marks)

Ridge count: 19

The line must touch the ridge to be counted.

Plain Arch

Ridges enter on one side and flow or tend to flow out the other side with a rise or wave in the center.

Tented Arch

Ridges enter on one side and flow or tend to flow out the other side, however the ridges in the center do not. This possesses an angle.

Tented Arch

Tented arch possessing the up-thrust.

Plain Whorls

The plain whorl has two deltas and at least one ridge making a complete circuit, which may be spiral, oval, circular, or any variant of a circle.

If an imaginary line drawn between both deltas crosses or touches a recurving ridge in the inner pattern area, the pattern is consider a plain whorl.

Central Pocket Loop

The central pocket loop has two deltas and at least one ridge which makes or tends to make a complete circuit. The circuit may be spiral, oval, circular or any variant of a circle. An imaginary line drawn between the two deltas must not touch or cross any recurving ridges within the inner pattern.

Double Loop

The double loop consists of two separate loop formations, with two separate and distinct sets of shoulders and two deltas.

Accidental

The accidental is a pattern consisting of a combination of two different types of patterns, with the exception of the plain arch, with two or more deltas; or a pattern which possesses some of the requirements for two or more different types; or a pattern which conforms to none of the definitions.

Major Parts of Prints

• Pattern area: appears in a loop or whorl in which appear the cores, deltas and ridges

• Core: approximate center of the print• Delta: that point on a ridge at or in front of and

nearest the center of the divergence of the type lines

Pattern Area

Core and Delta

Delta

Core

Fingerprint ClassificationHenry System

Key Major Primary Secondary Subsecondary final

20 M 1 U IOI 10

L 1 U IOI Sample classification

Primary Classification

• Primary: Values of whorlsFinger value assignments:Fingers 1 & 2: 16Fingers 3 & 4: 8Fingers 5 & 6: 4Fingers 7 & 8: 2Fingers 9 & 10: 1

• 1 is added to all primary classifications

• 1 over 1 indicates no whorls

• 32 over 32 indicates no whorls

Primary Classification

Even fingersOdd fingers

Where whorls appear in the fingers, the values are added, even over odd, with 1 added to the total.

In this card, the right hand has 16+8+4+1=29

The left hand:16+2+1=19

Secondary Classification

• Secondary: the pattern appearing in the index fingers

A ArchT Tented ArchR Radial LoopU Ulnar LoopW Whorl

Subsecondary Classification

• Subsecondary: grouping according to the ridge counts of loops and ridge tracings of whorls

Major Classification

• Major: Where whorls appear in the thumbs, the major division reflects whorl tracings (inner, outer, meeting)

• If loops appear in the thumbs, ridge counts are used

Major Classification Table

Left Thumb Denominator Right Thumb Numerator

01-11 Small………………………..[01-11, Small]

[12-16, Medium]

[17+, Large]

12-16 Medium…………………….. [01-11, Small]

[12-16, Medium]

[17+, Large]

17 or more, Large…………………..[01-17, Small]

[18-22, Medium]

[23+, Large]

Final Classification

• Final: ridge count of the right little finger.

*If not: ridge count in the left little finger*If not: a whorl is used * left delta to core (right hand) * right delta to core (left hand)

Key Classification

• Key: ridge count of the first loop appearing on the fingerprint card, exclusive of little fingers

Fingerprint Processing

• Powder and brush• Physical developer• Small particle developer• Ninhydrin• Cyanoacrylate• Iodine crystals

The following images depict laboratory practicums of the junior Fingerprints and Impressions class.

Powder and Brush

Powder and Brush

A camel hair brush is used to apply the fingerprint powder on suspect areas.

Powder and Brush

Once a print is developed, excess powder is brushed away, leaving a visible print.

Powder and Brush

Here, a hinge lifter is used to lift the developed print. Once applied, the print is preserved.

Powder and Brush

Powder and Brush

The lift needs to be one fluid motion.

Powder and Brush

Physical Developer

Documents can be washed with maleic acid and placed into the developer (yellow bath).

Physical Developer

Physical Developer

The sample should be agitated for 5 to 15 minutes, or removed at the best print.

Physical Developer

The physical developer produces a dark fingerprint when applied to latent prints.

Small Particle

Small particle reagent is sprayed on areas of suspected latent prints. Primarily used for wet surfaces, the reagent dries leaving behind a “powdered” fingerprint.

Ninhydrin

Ninhydrin is used on paper products. Purple fingerprints are developed after drying for 36 hours; or heat can be applied to quicker results.

Ninhydrin

A household hair dryer produces enough heat. Heat the sample approximately 2-3 minutes.

Ninhydrin

Ninhydrin developed latent fingerprints.

Cyanoacrylate Wand

The wand is heated by butane. The brass tip contains cyanoacrylate (super glue).

Cyanoacrylate

Cyanoacrylate, or “super glue”, hardens fingerprints into white crystalline prints. Vaporization occurs with heat and humidity.

Iodine Crystals

Iodine can be fumed at low temperatures. Once vaporous, it develops reddish-brown fingerprints.

Iodine Crystals

The specimen is placed into an air-tight container along with iodine crystals.

Iodine Crystals

Iodine is supplied in glass ampules.

Iodine Crystals

The air-tight container prevents the escape of iodine vapors.

Iodine Crystals

Heat from the hand is sufficient to vaporize the crystals. A hair dryer produces quicker results.

Iodine Crystals

An iodine fingerprint. Since iodine evaporates quickly, prints should be photographed.

Post Mortem Prints

Kits are available for collecting fingerprints from deceased persons.

Post Mortem Prints

Each finger is inked with the porelon pad.

Post Mortem Prints

The finger is then pressed into the concave scoop which holds the print card.

Post Mortem Prints

All deceased persons should be printed. Once buried or cremated, prints are no longer available.

Automated Technology

Computer programs can now match finger-prints. The latent print (left) is matched to the record print (right).

Record Fingerprints

Ten-print fingerprint card.

Major Case Prints

Major case prints represent all friction ridge surfaces of the fingers and palm.

Major Case Prints

Right palm with both outer blades of the hand. Palms are rolled.