Is there a relationship between fingerprint donation and DNA shedding?

This research investigates the possible relationship between fingerprint donation and DNA shedding. Volunteers were asked to provide a series of fingerprint depletions on glass. The level of fingerprint detail developed and DNA profiling results obtained were compared for each donor to investigate whether a relationship between fingerprint donation and DNA shedding exists. Our results suggest that between comparisons of donors, there is no statistical difference between the left and right hand of our volunteers in terms of fingerprint donation, but there is a statistical difference in terms of DNA shedding with three of our eight donors. Our results also indicate that there is no correlation between fingerprint donation and DNA shedding, meaning that an enhanced fingerprint with full ridge detail will not necessarily give a full DNA profile. In serious crime, these two avenues of evidence must be explored

The recoverability of fingerprints on paper exposed to elevated temperatures - Part 1: comparison of enhancement techniques

This research investigates the recoverability of fingerprints which have been exposed to elevated temperatures in order to mimic the environment a piece of paper may be exposed to within an arson scene. Arson is an expensive crime, costing the UK economy, on average, £53.8 million each week [1]. Anything which may give rise to the identity of the fire setter should be analysed and as such, unburnt paper may be a potential source of fingerprints. While it is true that even a moderate fire will obscure and render partially useless some types of evidence, many items, including fingerprints, may still survive [2-4]. This research has shown that fingerprints are still retrievable from paper which has been subjected to the maximum testing conditions of 200˚C for 320min. In fact, some fingerprints naturally enhance themselves by the heating process. This investigation has also shown that the most effective enhancement technique was found to be 1,8-diazafluoren-9-one (DFO) for exposure temperatures upto 100˚C. Physical developer (PD) is the most effective enhancement technique for exposure temperatures from 100˚C to 200˚C. For porous surfaces, there are fingerprint development techniques which are effective at enhancing fingerprints exposed upto a temperature of 200˚C, irrespective of the firefighting extinguishing technique, as PD, in addition to developing fingerprints exposed to high temperatures, is one of the few processes which will enhance fingermarks on wetted surfaces

The recoverability of fingerprints on paper exposed to elevated temperatures - Part 2: natural fluorescence

Previous work by the authors [1] investigated the recoverability of fingerprints on paper which had been exposed to elevated temperatures by comparing various chemical enhancement techniques (ninhydrin, 1,8-diazafluoren-9-one (DFO), and physical developer (PD)). During that study, it became apparent, as a consequence of observations made in operational work [2], that fingerprints on paper subjected to 150˚C fluoresced under examination with green light of waveband 473-548nm with a 549nm viewing filter. This work examined the three types of prints (eccrine, sebaceous, and ungroomed) after 20 min exposure to the temperature range 110˚C to 190˚C (in 10˚C increments) and found that the eccrine fingerprints fluoresced more brightly. This indicated that it was a component of the eccrine deposit which was causing the fluorescence. Luminance measurements found that the maximum fluorescence was experienced at 170˚C on both types of paper. As a consequence, eccrine heat-treated fingerprints were viewed under violet-blue (350-469nm), blue (352-509nm), and green light (473-548nm) which indicated that the greatest luminance intensities were obtained under blue light and the smallest under green light. In order to determine what component of the eccrine fingerprint was causing this fluorescence, five of the most prevalent amino acids (alanine, aspartic acid, glycine, lysine, and serine) [3-4] were exposed to this temperature range. The luminance measurements were taken under exposure to the green light in order for the minimum fluorescence to be observed, with an assumption that blue-violet or blue illumination will provide brighter fluorescence in practice. The results indicated that four of the amino acids are behaving similarly across the temperature range, but with slightly different luminance measurements, but all are exhibiting some level of fluorescence. Thermal degradation products of alanine and aspartic acid have been suggested by Richmond-Aylor et al. [5]. The structure of these thermal degradation products is cyclic in nature, and as such, there is a possibility that two of these products would fluorescence. Sodium chloride and urea were also exposed to the temperature range and they also fluoresced to some extent. This work shows that eccrine fingerprints that have been exposed to temperatures of between 130˚C to 180˚C will fluoresce under violet-blue, blue, and green light. This level of fluorescence for ungroomed fingerprints is much less but this will be dependent on the individual, the more eccrine the deposit, the stronger the fluorescence. This work shows that the amino acids, sodium chloride, and urea present in fingerprint deposits are all contributing to the fluorescence of the print, but may not be the sole contributor as other eccrine components have not yet been tested

Assessing phosphomolybdic acid as a fingermark enhancement reagent

The efficacy of an ethanolic solution of phosphomolybdic acid (PMA) was investigated as a latent fingermark visualization reagent, primarily on porous substrates. After treating samples and exposing them to ultraviolet radiation, the PMA solution was shown to develop fingermarks of high quality. Unlike the common amino acid reagents that are used for the development of fingermarks on porous substrates (e.g., ninhydrin and 1,8 diazafluoren-9-one), PMA stains a range of other compounds that are found in fingermark deposits, including lipids. The lysochrome diazo dye Oil Red O (ORO) was used for comparative purposes because of its application in staining some of the same components of fingermark residues for which PMA would be proposed. Initial results indicate that PMA is comparable to ORO at developing fingermarks on porous surfaces and may also have applications on nonporous surfaces

Polymerisation of S2N2 to (SN)(x) as a tool for the rapid imaging of fingerprints removed from metal surfaces

Polymerisation of S2N2 to (SN)x on metallic surfaces is induced by interaction with the minute corrosion signatures of removed (by washing) fingerprints; as vapour-phase S2N2 is employed, it follows that the process has the potential to rapidly screen large/convoluted metal pieces, such as explosive device fragments whose prints were wiped by the detonation

Visualisation of latent fingermarks on polymer banknotes using copper vacuum metal deposition: a preliminary study

The UK's recent move to polymer banknotes has seen some of the currently used fingermark enhancement techniques for currency potentially become redundant, due to the surface characteristics of the polymer substrates. Possessing a non-porous surface with some semi-porous properties, alternate processes are required for polymer banknotes. This preliminary investigation explored the recovery of fingermarks from polymer notes via vacuum metal deposition using elemental copper. The study successfully demonstrated that fresh latent fingermarks, from an individual donor, could be clearly developed and imaged in the near infrared. By varying the deposition thickness of the copper, the contrast between the fingermark minutiae and the substrate could be readily optimised. Where the deposition thickness was thin enough to be visually indistinguishable, forensic gelatin lifters could be used to lift the fingermarks. These lifts could then be treated with rubeanic acid to produce a visually distinguishable mark. The technique has shown enough promise that it could be effectively utilised on other semi- and non-porous substrates

Non-invasive detection and chemical mapping of trace metal residues on the skin

Residual traces of the metals copper and lead on an individual's skin may be elucidated by reaction of rubeanic acid with a gelatine lift taken from the target area in question, yielding intensely coloured reaction products. This non-invasive technique has been shown to offer promise in chemically mapping the distribution of the minute metal residues across an individual's hand deposited through touching metal items, a technique with potential forensic significance

Polymerisation of S2N2 to (SN)x as a tool for the rapid imaging of fingerprints removed from metal surfaces

This article was published in the Journal of Materials Chemistry [© Royal Society of Chemistry] and the definitive version is available at: http://dx.doi.org/10.1039/C0JM02724CPolymerisation of S2N2 to (SN)x on metallic surfaces is induced by interaction with the minute corrosion signatures of removed (by washing) fingerprints; as vapour-phase S2N2 is employed, it follows that the process has the potential to rapidly screen large/convoluted metal pieces, such as explosive device fragments whose prints were wiped by the detonation

The recoverability of fingerprints on nonporous surfaces exposed to elevated temperatures

Previous work by the authors compared the effectiveness of ninhydrin, 1,8-diazafluoren-9-one (DFO), and physical developer (PD) as enhancement reagents for fingerprints deposited on paper that had been exposed to elevated temperatures. This research extends the previous study and investigates the recoverability of fingerprints deposited onto glass and ceramic surfaces in order to mimic the environment these surfaces may be exposed to within a fire scene. This research has shown that ridge detail is still retrievable from ceramic after exposure to 800 °C (1472 °F) for 20 minutes, although, at temperatures in excess of 350 °C (662 °F), ridge detail would only survive if the fingerprints had been protected from direct exposure to radiant heat and direct air flow across the surface. This investigation has shown that the most effective enhancement technique overall was found to be superglue followed by BY40 at all temperatures except 200 °C (392 °F) in which case, iron powder suspension was superior. However, superglue followed by BY40 may have to be excluded as a prospective enhancement technique for many situations because the nonporous surface may become wet during firefighting activity. The use of silver vacuum metal deposition has been demonstrated to develop fingerprints after exposure to higher temperatures and may have future potential for this application

Fingerprint Development Techniques: Theory and Application

A comprehensive review of the latest fingerprint development and imaging techniques