Molecular composition of fingermarks: Assessment of the intra- and inter-variability in a small group of donors using MALDI-MSI

To date, a considerable amount of research has been devoted to the study of fingermark composition to serve many goals, such as the assessment of variability between donors, the impact of detection sequences, the understanding of detection mechanisms, and the determination of the donor's gender, age or lifestyle. These developments raise the question of the degrees of variability and consistency over time, characterizing the secretion residue between individuals or for a given donor. In this preliminary study, the use of Matrix-Assisted Laser Desorption/Ionization combined with Mass Spectrometry and Imaging (MALDI-MSI) was investigated to explore the intra- and intervariability of the secretion residue composition. The combined use of MALDI-MSI with chemometrics tools permitted to sort fingermarks according to their type (i.e., eccrine, sebum-rich, or natural), to emphasize a short-term consistency of composition for a given donor, and to differentiate fingermarks from four individuals. These results support the use of MALDI-MSI to investigate to which extent the fingermark composition may vary or remain consistent over time. This research will be pursued by considering a larger set of donors and an extended period of time. Ultimately, it is expected to assess how chemometric analysis of secretion residue composition could benefit research and investigative purposes linked to fingermarks