Relevant visualization technologies for latent fingerprints on wet objects and its challenges: a review <s> Background <s> The enhancement of latent fingerprints, both at the crime scene and in the laboratory using an array of chemical, physical and optical techniques, permits their use for identification. Despite the plethora of techniques available, there are occasions when latent fingerprints are not successfully enhanced. An understanding of latent fingerprint chemistry and behaviour will aid the improvement of current techniques and the development of novel ones. In this study the amino acid and fatty acid content of 'real' latent fingerprints collected on a non-porous surface was analysed by gas chromatography-mass spectrometry. Squalene was also quantified in addition. Hexadecanoic acid, octadecanoic acid and cis-9-octadecenoic acid were the most abundant fatty acids in all samples. There was, however, wide variation in the relative amounts of each fatty acid in each sample. It was clearly demonstrated that touching sebum-rich areas of the face immediately prior to fingerprint deposition resulted in a significant increase in the amount of fatty acids and squalene deposited in the resulting 'groomed' fingerprints. Serine was the most abundant amino acid identified followed by glycine, alanine and aspartic acid. The significant quantitative differences between the 'natural' and 'groomed' fingerprint samples seen for fatty acids were not observed in the case of the amino acids. This study demonstrates the variation in latent fingerprint composition between individuals and the impact of the sampling protocol on the quantitative analysis of fingerprints. <s> BIB001 </s> Relevant visualization technologies for latent fingerprints on wet objects and its challenges: a review <s> Background <s> In the context of evidence derived from the comparison of friction ridge skin impressions, the standards of proof commonly used by practitioners are reviewed. It is shown that from an early pragmatic guide given in 1914 by Edmond Locard, the practice has broadly evolved into to two main approaches. <s> BIB002 </s> Relevant visualization technologies for latent fingerprints on wet objects and its challenges: a review <s> Background <s> Fingerprints are the world’s oldest means of individual identification, and most of the work completed by CSIs hinges on latent fingerprinting and impression evidence. Many processes are available to reveal hidden physical evidence, and this chapter provides a look at those procedures that have been scientifically proven and accepted in court. <s> BIB003 </s> Relevant visualization technologies for latent fingerprints on wet objects and its challenges: a review <s> Background <s> Biometric databases attempt to identify people from biological and physical differences. Some (very) old methods for identifying people were branding, tattooing, and maiming; this is not popular today. This kind of data goes back to naive biometrics that start with simple photographs, then moved to Bertillon’s measurement system, and finally to various fingerprinting systems. The Bertillon system evolved into machine-collected and precise measurements. Facial recognition evolved from human judgment to photographic and geometric-based computerized systems. Finally, we added retina prints and then moved to DNA to get human identity within 600 billion possibilities. <s> BIB004 </s> Relevant visualization technologies for latent fingerprints on wet objects and its challenges: a review <s> Background <s> Physical developer (PD) is a fingermark development technique that deposits silver onto fingermark ridges. It is the only technique currently in routine operational use that gives results on porous substrates that have been wet. There is a reasonable understanding of the working solution chemistry, but the chemical constituent(s) contained in fingermark residue that are specifically targeted by PD are largely unknown. A better understanding of the PD technique will permit a more informed selection of alternative or complementary detection methods, and greater usage in operational laboratories. Recent research by our group has shown that PD does not selectively target the lipids present in the residue. This research investigated the hypothesis that PD targets the eccrine constituents in fingermark residue. This was tested by comparison of PD and indanedione-zinc (Ind-Zn) treated natural fingermarks that had been deposited successively, and marks that had been deposited with a ten second interval in between depositions. Such an interval allows for the regeneration of secretions from the pores located on the ridges of the fingers. On fingermark depletions with no time interval between depositions, PD and Ind-Zn treated depletions successively (and comparatively) decreased in development intensity as the amount of residue diminished. Short time intervals in between successive depletions resulted in additional secretions from the pores intermittently occurring, the increased development of which was visualised by treatment with both PD and Ind-Zn. The changes in development intensity were seen with both techniques on the same split depletions in a series, comparably and proportionately. These results indicate that the components targeted by PD are contained in the material excreted by the friction ridge pores through its mirrored development with Ind-Zn. Repetition of the experiments on marks that only contained eccrine material showed good Ind-Zn development but poor results with PD. This indicates that there are other constituents contained in "natural" fingermarks that are required to be present for PD to be able to target constituents in the eccrine sweat. It may be that the required constituents in the natural residues are non-water soluble, and that these protect the eccrine constituents from solubilisation in the aqueous washes employed in the PD method. Further research is being undertaken to determine whether PD is targeting specific compounds in the pore secretions, or a mixture of compounds consisting of the eccrine material, epidermal lipids and sebaceous lipids typically present in latent fingermark residues. <s> BIB005 </s> Relevant visualization technologies for latent fingerprints on wet objects and its challenges: a review <s> Background <s> Friction ridge examination is one of the bedrock disciplines in forensic science and has been employed for over 100 years. It is considered the pre-eminent method of individualization in forensic science. That status, however, has recently been upset by court challenges and high-profile misidentifications. Friction ridge examination will no doubt continue as a mainstay of forensic science, but changes in methodology and interpretation may be on the horizon. How the discipline weathers these changes depends on the willingness of the profession to critically examine their foundations, procedures, and methods. <s> BIB006 </s> Relevant visualization technologies for latent fingerprints on wet objects and its challenges: a review <s> Background <s> Abstract In order to address the need for consistency and generality in chemical methods developed for detection of latent fingerprints on paper substrates, a practical protocol was developed using 1,2-indanedione-based bi-functional reagents. A series of novel bi-functional reagents were designed and synthesized using a concise, five-step sequence. An optimized development condition that is tailored to the type of paper substrate that requires processing was discovered, allowing potential application in practical criminal work where evidence processing is an irreversible process. The study also provided an insight to the underlying mechanism of interaction between the bi-functional reagent and fingerprint residue. <s> BIB007 </s> Relevant visualization technologies for latent fingerprints on wet objects and its challenges: a review <s> Background <s> Fingerprints have been used for human identification in criminal investigation for over 100 years. The detection of invisible or latent marks at crime scenes has been one of the great scientific challenges in forensic science and there have been considerable advances in this capability. The technological age and increasing power of computing has had a major influence on fingerprint identification providing the capacity to search large databases and provide rapid identification of persons of interest. This chapter discusses the important contribution of fingerprints to criminal investigation. <s> BIB008
Fingerprints and its evidential values  stated that the admissibility of fingerprints in the court of law has always been rested on the premise of its (a) individual characteristic, (b) persistency throughout an individual's lifetime, and (c) systematic classifications of general ridge patterns. The first principle stated that every individual, including identical twins, has its own distinctive fingerprints  BIB002  BIB003 BIB005 . Such uniqueness relies profoundly on the identity, number, and relative location of the minutiae ( Fig. 1 ) in point-by-point comparison of known and unknown prints  BIB006 . Owing to its physical attachment to the dermis  , fingerprints persist throughout an individual's lifetime, provided that there is no deep-seated injury that penetrates the dermal papillae of the skin  BIB006 . Nevertheless, such injury simply offers a new ridge characteristic which may be possibly valuable for identification   . Although the appearance of the prints may appear "less sharp" as a person ages, which corresponds to the loss of elasticity of the skin, the arrangement of friction ridge skin would remain unchanged  . Furthermore, fingerprints have general ridge patterns that can be systematically classified into loops, whorls, and arches ( Fig. 2 ) with its relative worldwide population percentages being 60-65%, 30-35%, and about 5%, respectively  BIB004 BIB003 BIB006 . In addition, these general patterns can be further classified into radial and ulnar loops, plain whorl, central pocket loop, double loop, accidental, as well as plain and tented arches  . Fingerprints can be defined as the impressions of friction ridge skin of fingers that are left on a surface of an object upon contact   BIB006 . For forensic applications, fingerprints fall into three different natures viz. latent, patent, and plastic  BIB005 BIB006 BIB008 . Being frequently encountered at crime scenes BIB001  BIB007 BIB008 , latent fingerprint continues to pose challenges to forensic scientists due to its problematic hidden nature, and hence necessitating the use of optical, physical, and/or chemical visualization methods for comparison and identification purposes  BIB005 BIB006 . Patent fingerprints are readily visible prints upon contact with transferable colored media (e.g., blood and paint), whereas plastic fingerprints refer to the impressions made on soft, malleable objects (e.g., putty and wax)   BIB005 BIB006 , making them relatively easier for forensic analysis, as opposed to that of the latent ones.