Friction RidgeFriction RidgeIdentificationIdentification

Created as a supplement toCreated as a supplement to

Chapter 15 ofChapter 15 of

Fingerprint IdentificationFingerprint Identification

By William LeoBy William Leo

Copyright Copyright © © 20042004

All Rights ReservedAll Rights Reserved

““Workers familiar with finger-print minutiae Workers familiar with finger-print minutiae all affirm that there are no two duplicate all affirm that there are no two duplicate prints of different fingers. They recognize prints of different fingers. They recognize many qualities other than the mere many qualities other than the mere occurrences of details. The minutiae, like occurrences of details. The minutiae, like total patterns, have individuality. The total patterns, have individuality. The interruption between two ridge ends may interruption between two ridge ends may be short or long, the ridges may or may not be short or long, the ridges may or may not deviate in direction as they terminate; deviate in direction as they terminate; bifurcations exhibit varying spreads, and bifurcations exhibit varying spreads, and many similar individual distinctions of many similar individual distinctions of minutiae occur.minutiae occur.

When all these finer qualities are When all these finer qualities are appreciated, it is not surprising that appreciated, it is not surprising that identifications of individuals are identifications of individuals are possible when only partial prints are possible when only partial prints are available.”available.”

Finger Prints, Palms and SolesFinger Prints, Palms and Soles

An Introduction to An Introduction to DermatoglyphicsDermatoglyphics

Doctors Harold Cummins & Doctors Harold Cummins & Charles MidloCharles Midlo

1943, Pages 154 & 1551943, Pages 154 & 155

All areas of friction skin ( fingerprints, All areas of friction skin ( fingerprints, palms, and the toes and soles of the palms, and the toes and soles of the feet) are:feet) are:

PermanentPermanent - Do not naturally - Do not naturally change with time.change with time.

Unique Unique - Therefore Allowing - Therefore Allowing individualizationindividualization

Ridge Features and Ridge Features and ClarityClarity

The level of clarity or quality of detail The level of clarity or quality of detail will determine the type of features will determine the type of features available for comparison and the available for comparison and the amount of detail needed to identify.amount of detail needed to identify.

This is why there is not a pre-This is why there is not a pre-determine standard as to the amount determine standard as to the amount of detail needed for an identificationof detail needed for an identification

Level 1 DetailLevel 1 Detail

Ridge FlowRidge Flow

Class Class characteristics only characteristics only – No individualizing – No individualizing detaildetail

Fingerprint patterns Fingerprint patterns and ridge flow and ridge flow (shape)(shape)

Level 2 DetailLevel 2 Detail

Individual Ridge Individual Ridge PathPath

Major ridge Major ridge featuresfeatures

Ridge endings, Ridge endings, bifurcations, etc, bifurcations, etc, their positions and their positions and relationship to relationship to other featuresother features

Allows Allows individualization individualization

Level 3 DetailLevel 3 Detail

Individual ridge Individual ridge AppearanceAppearance

Highest level of Highest level of detaildetail

Smallest features Smallest features (pore & ridge (pore & ridge structure) are visible structure) are visible for comparison.for comparison.

The most The most individualizing detailindividualizing detail

““A finger print is too complex a structure A finger print is too complex a structure and its numerous details, definite as they and its numerous details, definite as they are, are as arbitrary in their occurrence are, are as arbitrary in their occurrence and arrangement as are the pebbles on and arrangement as are the pebbles on the beach, no square foot of which could the beach, no square foot of which could ever be duplicated by any other. It is ever be duplicated by any other. It is always so with natural objects; the details always so with natural objects; the details are so numberless, and so independent of are so numberless, and so independent of the rest, that there are no duplicates.”the rest, that there are no duplicates.”

Personal Identification, Page 324-325Personal Identification, Page 324-325

Wilder PhD and Wentworth, 1918 Wilder PhD and Wentworth, 1918

The Identification ProcessThe Identification Process The ACE/V MethodThe ACE/V Method

AnalysisAnalysis ComparisonComparison EvaluationEvaluation PlusPlus VerificationVerification

AnalysisAnalysis The print is examined to determine The print is examined to determine

what detail is present and it’s quality what detail is present and it’s quality (levels of clarity). (levels of clarity).

Does the print contain sufficient Does the print contain sufficient detail to be compared and identified?detail to be compared and identified?

What area of friction skin may it have What area of friction skin may it have come from?come from?

ComparisonComparison

The unknown The unknown print is print is orientated to the orientated to the known exemplar.known exemplar.

A side by side A side by side comparison is comparison is made.made.

Possible ConclusionsPossible Conclusions

An identification (individualization)An identification (individualization)

An eliminationAn elimination

InconclusiveInconclusive

EvaluationEvaluation Is the detail (features) in agreement or in Is the detail (features) in agreement or in

other words are they the same?other words are they the same? If so an identification is made.If so an identification is made.

Is the detail (features) different?Is the detail (features) different? If so an elimination is madeIf so an elimination is made

If there is insufficient detail to I.D. or If there is insufficient detail to I.D. or eliminate, the comparison would be eliminate, the comparison would be inconclusiveinconclusive

VerificationVerification The ACE process is repeated by another The ACE process is repeated by another

examiner – independently examiner – independently

This is done as a quality control and to This is done as a quality control and to identify errors.identify errors.

The fact that results can be repeated or The fact that results can be repeated or duplicated independently demonstrates duplicated independently demonstrates that fingerprint identification is not that fingerprint identification is not subjective.subjective.