Fingermark submission decision-making within a UK fingerprint laboratory: do experts get the marks that they need?

Within UK policing it is routinely the responsibility of fingerprint laboratory practitioners to chemically develop areas of latent fingerprint ridge detail on evidential items and to determine which areas of ridge detail are of sufficient quality to be submitted to fingerprint experts for search or comparison against persons of interest. This study assessed the effectiveness of the fingermark submission process within the Evidence Recovery Unit Fingerprint Laboratory of the Metropolitan Police Service. Laboratory practitioners were presented with known source fingermark images previously deemed identifiable or insufficient by fingerprint experts, and were asked to state which of the marks they would forward to the Fingerprint Bureau. The results indicated that practitioners forwarded a higher percentage of insufficient fingermarks than is acceptable according to current laboratory guidelines, and discarded a number of marks that were of sufficient quality for analysis. Practitioners forwarded more insufficient fingermarks when considering fingermarks thought to be related to a murder and discarded more sufficient fingermarks when considering those thought to be related to a crime of 'theft from vehicle'. The results highlight the need for fingerprint laboratories to work alongside fingerprint experts to ensure that a consistent approach to decision-making is, as far as possible, achieved, and that appropriate thresholds are adopted so as to prevent the loss of valuable evidence and improve the efficiency of the fingerprint filtering process.