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New CSAFE Study Analyzes Real-world Latent Print Comparison Casework

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A recently published analysis of latent print comparison cases from a large metropolitan crime lab sought to understand different workflows and case outcomes.

Latent print research has mainly focused on estimating error rates and identifying potential areas of concern within latent print conclusions made in artificial, controlled environments. Brett Gardner, a Center for Statistics and Applications in Forensic Evidence (CSAFE) researcher and co-author of the study, said almost no research has examined actual latent print casework to determine typical analysis procedures and outcomes.

“Basic examination of lab case processing is sorely needed,” said Gardner, “In an effort to expand the literature, we examined actual, real-world casework from a latent print unit.”

Figure 1 from the study: A flowchart depicting prints examined by the Houston Forensic Science Center latent print unit in 2018.
Figure 1 from the study: A flowchart depicting prints examined by the Houston Forensic Science Center latent print unit in 2018. Click on image to enlarge.

The study, published in Forensic Science International, describes casework completed by the Houston Forensic Science Center (HFSC) latent print unit during one calendar year, including a unique workflow that involves Preliminary AFIS Associations, or potential identifications that are reported out as investigative leads. AFIS stands for automated fingerprint identification systems.

Gardner, a postdoctoral researcher from the University of Virginia; Sharon Kelley, an assistant professor at the University of Virginia; and Maddisen Neuman, a quality/research associate at HFSC, analyzed latent print comparison cases with published reports dated in 2018. The reports included offense type, examiner sufficiency determination, anatomical source, AFIS database search and subsequent results based on AFIS output. The reports were from 17 latent print examiners with work experience ranging from 5 to 36 years.

Gardner and his colleagues began by tracking key case processing details. They sought to describe the prevalence of examiner conclusions during one year, explore whether examiner conclusions varied according to casework variables and review the extent to which there were examiner differences in conclusions and case processing.

In 2018, HFSC examined 2,975 cases with 3,239 related requests for analysis, representing a total of at least 20,494 prints. The researchers found that approximately 45 percent of all examined prints were determined to be of sufficient quality to enter into AFIS, and 22 percent of AFIS entries resulted in potential identifications.

HFSC examiners conducted 11,812 searches in AFIS, first using a county-wide AFIS. If the prints did not produce an association, subsequent searches were made in a statewide AFIS, and any remaining prints were searched in the federal AFIS. Most searches were conducted at the county level.

Based on their analysis of the latent print casework from HFSC, Gardner and his colleagues found variations in examiner conclusions and AFIS outcomes based on case details, print source and AFIS database. Also, examiners differed in the number of cases processed, and their rates of sufficiency determinations and AFIS conclusions, Gardner said.

Regarding future research in this area, Gardner noted that comparing the workflow and outcomes of multiple labs would offer more context and provide a better understanding of the differences in case processing and case outcomes.

“These real-world results are an important step in understanding and ultimately improving the practice of latent print examination among active crime laboratories,” said Gardner. “We hope these findings serve as a launching point for future research on the latent print comparison process.”

View and download the journal article at https://lib.dr.iastate.edu/csafe_pubs/78/.

Insights: Latent Print Comparison and Examiner Conclusions

Learn more about CSAFE’s research on latent print analysis at https://forensicstats.org/latent-print-analysis/.

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