The forensic exploitation of fingermark chemistry: A review

Abstract

The substances deposited from the fingertip onto a surface during contact between them represent a highly complex range of chemicals that can be exploited in a variety of ways in a forensic investigation. An overview is given of the multitude of chemicals that have been detected in fingermarks, including those occurring in endogenous sweat, metabolites of ingested substances, and exogenous substances picked up on the fingertip. Changes in chemistry that may occur between deposition of the fingermark and its subsequent forensic analysis are discussed, with particular reference to the ways in which these changes have been considered as a means of dating fingermarks. The ways in which fingermark enhancement reagents utilize the different chemicals present to reveal ridge is reviewed, together with how different classes of chemical can be sequentially targeted to optimize the number of fingermarks recovered.A field of increasing interest is the use of advanced analytical techniques incorporating mass spectrometry and imaging capability to simultaneously obtain additional contextual information about the donor of the mark while visualizing the fingermark ridge pattern. Examples are given of how such information can be applied in forensic investigations. It is concluded that an extensive "tool kit" of fingermark enhancement processes is already available to utilize the different chemicals present, and the advances that can be made in this field using conventional approaches are limited. There is, instead, significant potential to utilize analytical techniques to forensically exploit the chemical information within fingermarks but there are also significant barriers to their implementation in this way.

Application of MALDI MS imaging after sequential processing of latent fingermarks

“…In a few cases, it has been possible to show that MALDI MSI provided additional ridge detail in partially developed or empty marks [19]. In line with previous reports on constituents availability after the application of a single FET [1], MALDI is able to detect and image constituents or classes of compounds even after being targeted by a prior FET [19,22] and even in specimens over 30 years old [9]. Additionally, four examples have been published in which MALDI MSI was shown to be compatible with fingermark sequential processing.…”

“…Latent fingermarks are routinely visualised by subjecting them to one or more crime scene investigation (CSI)/crime lab processes to maximise recovery of ridge flow and minutiae permitting an identification. Sequential processing is possible as a single chemical development reagent can still leave a considerable proportion of fingermark constituents that can be targeted by an additional enhancement technique [1]. When these enhancement techniques are used in a sequence, an optimum order of application is recommended , starting from the least destructive when possible, to maximise the biometric detail that can emerge from the different fingermark constituents.…”

Visualisation of Amphetamine Contamination in Fingerprints Using TOF-SIMS Technique

“…or even by handshakes between a smoker and a non-smoker [ 8 , 9 ]. The last few years have shown an increasing application of various chemical imaging techniques in forensic science [ 10 , 11 , 12 , 13 , 14 , 15 ], especially in detecting exogenous materials present on fingermarks, such as particles of nicotine [ 9 ], gunshot residues [ 16 , 17 , 18 , 19 ], illicit drugs [ 6 , 7 , 8 , 18 , 19 , 20 , 21 , 22 , 23 ], caffeine [ 24 , 25 ], blood [ 26 ], explosive RDX residues [ 20 , 27 ], or in determining the sequencing of fingerprint and ink signals on documents [ 28 , 29 ].…”

Monitoring the chemical changes in fingermark residue over time using synchrotron infrared spectroscopy

“…Fingermark residue is made primarily of a mixture of secretions from the eccrine and sebaceous glands, and is likely to be contaminated with constituents picked up through contact during daily activity. [4][5][6] Once deposited, this residue is not static with a potential to move across a surface, and undergo chemical and physical changes. Sebaceous material is an oily mixture of lipids, which are known to degrade over time, studies have attempted to correlate this rate of degradation to time since fingermark deposition.…”

“…12,18 Keisar et al calculated the mass of a fingermark to be between 2 -9 µg, based on the weight of a smaller subsection of the mark, whilst Bleay et al reported a mass range of 0.33 -29 µg. 6,18 Several studies have explored fingermark degradation, by visually comparing how fingermark development methods are affected by evaporation and time since deposition. 14,17,20,21 An alternative approach has been to explore the chemical alteration within fingermark residue, by directly measuring the chemical constituents present at different time points since deposition, using techniques such as gas chromatography (GC) and liquid chromatography -mass spectroscopy (LC-MS).…”