has been directed toward developing population statistics, although more would be feasible.24

Methods of Interpretation

The determination of an exclusion can be straightforward if the examiner finds detail in the latent print that does not match the corresponding part of the known print, although distortions or poor image quality can complicate this determination. But the criteria for identification are much harder to define, because they depend on an examiner’s ability to discern patterns (possibly complex) among myriad features and on the examiner’s experience judging the discriminatory value in those patterns. The clarity of the prints being compared is a major underlying factor. For 10-print fingerprint cards, which tend to have good clarity, even automated pattern-recognition software (which is not as capable as human examiners) is successful enough in retrieving matching sets from databases to enjoy widespread use. When dealing with a single latent print, however, the interpretation task becomes more challenging and relies more on the judgment of the examiner. The committee heard presentations from friction ridge experts who assured it that friction ridge identification works well when a careful examiner works with good-quality latent prints. Clearly, the reliability of the ACE-V process could be improved if specific measurement criteria were defined. Those criteria become increasingly important when working with latent prints that are smudged and incomplete, or when comparing impressions from two individuals whose prints are unusually similar.

The fingerprint community continues to assert that the ability to see latent print detail is an acquired skill attained only through repeated exposure to friction ridge impressions. In their view, a lengthy apprenticeship (typically two years, at the FBI Laboratory) with an experienced latent print examiner enables a new examiner to develop a sense of the rarity of features and groups of features; the rarity of particular kinds of ridge flows; the frequency of features in different areas of the hands and feet; the degree to which differences can be accounted for by mechanical distortion of the skin; a sense of how to extract detail from background noise; and a sense of how much friction ridge detail could be common to two prints from different

24

See, e.g., E. Gutiérrez, V. Galera, J.M. Martínez, and C. Alonso. 2007. Biological variability of the minutiae in the fingerprints of a sample of the Spanish population. Forensic Science International 172(2-3):98-105. For information about the basic availability of data, see C. Champod, C.J. Lennard, P.A. Margot, and M. Stoilovic. 2004. Fingerprints and other ridge skin impressions. Boca Raton, FL: CRC Press; D.A. Stoney. 2001. “Measurement of Fingerprint Individuality.” In: H.C. Lee and R.E. Gaensslen (eds.). Advances in Fingerprint Technology. 2nd ed. Boca Raton, FL: CRC Press; pp. 327-387.



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