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Strengthening Forensic Science in the United States: A Path Forward
Analysis, Study and Technology (SWGFAST) offers a guideline, “Training to Competency for Latent Print Examiners.”18 Although these are excellent resources, they are not required, and there is no auditing of the content of training programs developed by nonaccredited agencies. The IAI also offers a certification test that measures both the knowledge and skill of latent print examiners; however, not all agencies require latent print examiners to achieve and maintain certification.
Method of Data Collection and Analysis
The technique used to examine prints made by friction ridge skin is described by the acronym ACE-V: “Analysis, Comparison, Evaluation, and Verification.”19 It has been described in forensic literature as a means of comparative analysis of evidence since 1959.20 The process begins with the analysis of the unknown friction ridge print (now often a digital image of a latent print). Many factors affect the quality and quantity of detail in the latent print and also introduce variability in the resulting impression. The examiner must consider the following:
Condition of the skin—natural ridge structure (robustness of the ridge structure), consequences of aging, superficial damage to the skin, permanent scars, skin diseases, and masking attempts.
Type of residue—natural residue (sweat residue, oily residue, combinations of sweat and oil); other types of residue (blood, paint, etc.); amount of residue (heavy, medium, or light); and where the residue accumulates (top of the ridge, both edges of the ridge, one edge of the ridge, or in the furrows).
Mechanics of touch—underlying structures of the hands and feet (bone creates areas of high pressure on the surface of the skin); flexibility of the ridges, furrows, and creases; the distance adjacent ridges can be pushed together or pulled apart during lateral movement; the distance the length of a ridge might be compressed or stretched; the rotation of ridge systems during torsion; and the effect of ridge flow on these factors.
Nature of the surface touched—texture (rough or smooth), flexibility (rigid or pliable), shape (flat or curved), condition (clean or dirty), and background colors and patterns.
SWGFAST. 2002. Training to Competency for Latent Print Examiners. Available at www.SWGFAST.org.
Ashbaugh, op. cit.; Triplette and Cooney, op. cit.; J. Vanderkolk. 2004. ACE-V: A model. Journal of Forensic Identification 54(1):45-52; SWGFAST. 2002. Friction Ridge ExaminationMethodology for Latent Print Examiners. Available at www.SWGFAST.org.
R.A. Huber. 1959-1960. Expert witness. Criminal Law Quarterly 2:276-296.