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Monday, November 5, 2007

 
The purpose of the Detail is to help keep you informed of the current state of affairs in the latent print community, to provide an avenue to circulate original fingerprint-related articles, and to announce important events as they happen in our field.
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Breaking NEWz you can UzE...
compiled by Jon Stimac

Science, tradition at war in forensics BALTIMORE SUN, MD - Oct 29, 2007 "Prosecutors in the Baltimore County case cannot appeal the decision, and they have asked the judge to reconsider her ruling."

'Radical' fingerprint decision challenged Examiner.com, WV - Oct 30, 2007 .“This [judge] stands alone in American jurisprudence in ruling that fingerprint identification evidence is not reliable enough to be admitted,”

Judge rejects request to toss out fingerprints  BALTIMORE SUN, MD - Nov 4, 2007 "...he had read and "respectfully" disagreed with the decision of Judge Susan M. Souder."

Southern California man held for 43-year-old murder ASSOCIATED PRESS - Nov 3, 2007  "Back in 1964, the process of collecting and matching fingerprints was all done manually," Gonzalez said.

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Recent CLPEX Posting Activity
Last Week's Board topics containing new posts
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Baltimore Judge declares Fingerprints not reliable.
Justice Pie 968 Sun Nov 04, 2007 7:04 pm

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wkpetroka 4059 Sun Nov 04, 2007 12:20 am

Statistics and Misidentifications - The weeks Detail
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Daubert case?
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DNA and Fingerprints
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and on a lighter note.....
Angie 392 Thu Nov 01, 2007 1:43 pm

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UPDATES ON CLPEX.com


Updated the Fingerprint Interest Group web page with FIG # 20.

Updated the Detail Archives

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Last week

we started a 3-part historical series on the rarity of features in friction ridge identification.

This week

we continue with part 2 of the series.

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The Reference Shelf (Santamaria Discussion)
by J. Hess
LAPD Latent Finger Print Section

In this column last month we stated that two studies dealing with the qualitative weight of various ridge characteristics based on their frequency of occurrence would be reported.

This month an idea from Spain will be discussed. The researcher involved is Florentino Santamaria Beltran. While Chief of the Technical Police Laboratory in Madrid, Spain, he delivered his outline to the International Criminal Police Organization (Interpol) at its assembly in Oslo, Norway, in 1953. He called the paper simply, “A New Method of Evaluating Ridge Characteristics.” The address was discussed in the August-September, 1953, issue of the International Criminal Police Review, the official publication of Interpol. The full report was published in the May, 1955, issue of Finger Print and Identification Magazine. In addition, Salil Kumar Chatterjee of India devotes a full chapter to Santamaria’s method in his book, “Finger-Palm and Sole Prints.”

Mr. Santamaria first made his premise public in 1942 at the First Spanish Congress of Forensic Medicine, held in Madrid. Apparently little notice was given his proposal at that time, outside of the Latin American countries, and due to internal conditions the author himself was unable to give his theory world-wide publicity until later.

His hypothesis is summed up in this quotation from his Oslo paper: “If the value of each characteristic is different, will it not be equally so for each collection of points?” “And if they are different, then why should we say, ‘You must have ten to twelve points to establish identity,’ taking into account of the individual value as though all points has the same value?”

“In other words, in the face of all logic the total identification value of ten to twelve ridge endings, bifurcations or convergences (which in addition to being invariable, occur very frequently) is at present considered to be equal to that of a collection of an equal number of characteristics points, one or more of which are very rare. This is a state of affairs which I consider should be corrected.”

Compiled Frequency Table
The theory advanced by Mr. Santamaria is based on a study of 1,000 prints and recording the frequency of occurrence of ten different types of ridge characteristics, per 1,000 ridges. He compiled a table of figures reflecting the number of times each characteristic appeared, and from this table grouped these characteristics and assigned relative weight to their occurrence in this manner:

FREQUENCY RANGE WEIGHTED VALUE

Very Frequent
     Ridge Ending 1
     Bifurcation 1
     Convergence 1
Frequent
     Enclosure 2
     Fragment 2
Rare
     Deviated Break 2
     Interjunction 2
     Interruption 2
     Point or Dot 2
     Changeover 2
Very Rare
     Intersection 3
     Return 3

By this method, a partial print having ten ridge endings with a value of 1 each would total 10, a valid identification. Another print might contain five ridge endings or bifurcations with a value of 1 each; one ridge dot with a value of 2; and one intersection, rated at 3; with a cumulative total of 10, equally as valid as identification. Thus one print containing but seven characteristic, with due consideration for the comparative value of each, would be as emphatic as one containing ten of the more common points of identity.

Other Features Weighted
In addition to weighting the points, he believes that certain “peculiarities” appearing in the print should add value to the identification. A print with a rarity or a lack of characteristic points, or a scar, or one showing abundant pore structure, would receive an additional value of 1 to be included in the total score. For example, if an area available for study had a total value of 9, but in addition contained one of these peculiarities, the total value would then be 10.

As might be expected, reaction from various finger print workers around the world was varied and ranged from near total acceptance, with minor modifications, by Peru, to a comment, “deplorable” from an Italian source. Following publication of the report by Finger Print And Identification Magazine, several subsequent issues contained a wealth of stimulating comment on Mr. Santamaria’s work, as well as other aspects of comparison and identification by some of the world’s leading friction ridge authorities.

Weakness Of The Proposal
At this point, the “New Method” would appear to be an improvement over out generally accepted “quantitative” system with its strictly arbitrary requirement for a given number of points of identity. This method would provide a measure of flexibility and allow the print examiner greater latitude of interpretation in considering factors other than mere numerical values. However, closer examination of the process by which these qualitative values were determined reveals yet another arbitrary factor. For example, the study shows that ridge endings occur at the rate of about 534 per 1,000 ridges, while bifurcations are present only some 282 times. Yet the weighted value assigned to each of these characteristics is 1. In the same 1,000 ridges, a ridge dot occurs about 22 times, but its value is 2, as compared to a ridge ending which would occur roughly 25 times more often. The obvious reply might then be, “Let’s discard this arbitrary value and give these individual characteristics their actual value, based on the frequency of occurrence.” But, would any print examiner what to depend upon one intersection for an identification, even though this characteristic appears only twice per 1,000 ridges as compared to 534 ridge endings?

Mr. Santamaria’s “New Method” summarizes many arguments advanced by print men the world over and probably applied in varying degrees by all of us at one time or another. Yet we find it hard to accept either his arbitrary values or the relative values established by actual occurrence ratio between various points. Neither method seems to offer a satisfactory solution, so as in many other areas of finger print work; there exists a need for additional research and study.

The next column will deal with the results of such a research by a worker in yet another part of the world.

(Grammar and spelling corrections made by Charles J. Parker 10-13-07)


(Originally printed in Finger Print and Identification Magazine, Vol. 52 No.; April 1971)

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