Occurrence and Utility of Latent Print Correspondences that are Insufficient for Identification

Latent prints that have insufficient characteristics for identification often have discernable characteristics that could form the basis for lesser degrees of correspondence or probability of occurrence within a population. Currently, those latent prints that experts judge to be insufficient for identification are not used as associative evidence. How often do such prints occur? What is their potential value for association? Would they actually impact case investigations or prosecutions in a useful way?

The answers are important. We could be routinely setting aside a very important source of associative evidence, with high potential impact, in many cases; or such prints may be of very low utility, adding very little, or only very rarely contributing to cases in a meaningful way. This project will address these questions, providing a factual basis to set the priority for development and validation of methods to exploit the use and associative value of these prints.

There are three, one-year Phases. In Phase I we will work with a range of state and local laboratories to measure how often, and at what levels of associative value, these prints occur in casework. A maximum potential associative value will be measured based on modeling within variability and between-variability of AFIS scores. This method incorporates (1) latest generation feature extraction, (2) a (minutiae-only) matcher, (3) validated distortion functions, and (4) NIST SD27 database calibration. Observed associative value distributions will be determined for violent crimes, property crimes, and for prints meeting existing objective measurements of latent print quality.

This will provide, for the first time, a measurement of the occurrence and associative value of NVID latents in casework. The actual usefulness of these prints depends on the case context. In Phase II we will work with investigators, prosecutors and crime laboratories to study prints found in well-defined case contexts. Phase II will answer whether, how often, and to what degree associations from these latent prints could answer questions of relevance within specific case contexts.

In Phase III we will (1) review our results with key constituencies (investigators, crime laboratories, attorneys and judges) to assess the practicality and effectiveness of this form of evidence, (2) incorporate selected measurement and/or process improvements, and (3) fill identified data gaps through additional collections and analyses. Project results will provide a reasonable measure of the extent to which latent prints that are currently set aside as “of no value for identification” can serve as useful associative evidence.

This project contains a research and/or development component, as defined in applicable law, and complies with Part 200 Uniform Requirements - 2 CFR 200.210(a)(14).

NCA/NCF