Utilizing Lesser Quality Latent Images to Exclude an Individual.

The court and attorneys are made aware when a latent image in a case is identified to the defendant or victim. The latent is often the critical piece of physical evidence in a case. What the court and attorneys may not be aware of are the latent images that are not verifiable or categorized as no value. I want to discuss the unverifiable or no value images, images that lack the quantity and clarity of detail for identification. What you may not know is the unverifiable or no value images can also play a significant a role in the identification process. These lesser quality images can sometimes be used to exclude an individual based on the one discrepancy rule. Simply a single difference in appearance between a latent print and a known fingerprint must preclude identification unless the examiner has a valid explanation for the difference. Distortions are not considered a discrepancy and not a basis for exclusion. The “Exclusion” is supported by the theories of biological uniqueness and permanence, probability modeling, and empirical data gained through more than one hundred years of operational experience.


Currently there is no uniform policy/procedure on how CSI units handle the collection and evaluation of latent fingerprint evidence. In some units the evaluation of the latent may be done at the crime scene other units may do it back at the Unit Lab. The evaluation of the latent in the controlled environment of the Lab. should produce a more accurate result. What is critical to an accurate analysis are the agency policy/procedures and qualifications of the full time latent examiner making the analysis. The designation of unverifiable or no value images may result in the images being discarded/destroyed that could be used to exclude an individual as the donor of the latent image. As is obvious, the more experienced latent examiner should produce a more accurate and uniform result. In the 80’s it was possible for the crime scene tech. to determine a latent prints usability in the field, but with today’s image enhancement tools, latent images require a a more experienced latent examiner make the initial evaluation on value.

In July of this year the International Association of Identification dropped its ban on qualified conclusions, and opened the door for future testimony based on probability models involving finger/palm print comparisons. In the not too distant future you can expect to see the unverifiable images coming into court as probable identifications. This new policy just amplifies the need to insure the initial latent image analysis is uniform and accurate insuring critical evidence is available to the court. This is situation is one where if the agency policies/procedures are not updated/maintained resulting loss of evidence could impact a prosecutor as badly as a defense attorney.



Bob McAuley Dir. Operations/Training Forensic Biometric Identification Solutions LLC.