Sequencing DNA sampling and fingerprint development using DNA-free consumables: fingermark obliteration versus DNA recovery is not a zero-sum game

Abstract

ABSTRACT The dual recovery of DNA samples and fingerprints from touched objects and surfaces is highly desirable for many criminal investigations as it provides greater probative value, particularly compared to relying solely on DNA evidence, which may be present due to secondary transfer or unresolvable due to a high number of contributors. Despite this, DNA sampling is generally given priority over fingerprint examination to minimize contamination even though the mechanical action of DNA sampling is generally thought to obliterate fingerprint residues. This study aimed to strengthen decision-making around sequencing fingerprints and DNA examinations by assessing whether any fingerprint ridge details remained after first sampling for DNA and whether DNA-free fingerprint brushes and powders were fit for purpose. The results demonstrated that DNA sampling and powder fingerprint development are not necessarily a zero-sum game. High-quality fingerprints were developed using DNA-free consumables without any contamination, and DNA sampling using tapelifts was shown to leave sufficient latent material to develop a fingerprint suitable for comparison whilst also generating a high-quality DNA profile. This represents valuable insight for informing evidence-based decision-making by forensic examiners for the optimal strategy for sequential examination and collection of critical fingerprint and DNA evidence.