Latent fingermark detection using functionalised silicon oxide nanoparticles: Optimisation and comparison with cyanoacrylate fuming

Fingermark quality assessment, a transversal study of subjective quality scales

Fingermark detection research aims to improve the quantity and quality of fingermarks detected through the development of novel techniques. Subsequently, there is a need to evaluate these methods to determine the quality of the developed mark. Since the 1980's there has been a significant number of publications, which utilise a variety of different quality assessment methods. The introduction of common practice methods from the International Fingerprint Research Group (IFRG) aimed to implement a more standardised approach. Although these schemes are recommended as common practice, they are only guidelines. Consequentially, there is currently no universally accepted method to evaluate the enhancement techniques implemented in research. Therefore, this study aimed to collate and analyse the published protocols being used within fingermark detection research in order to better understand their application and how research is currently analysing and interpreting fingermark quality. This study comprised of manual and automatic searches of over 2000 published papers within the fingermark detection area. After thorough analysis of the articles, 396 published papers were found to have used a scale within the years spanning 1998-2022. The number of publications that report the use of a scale to assess quality for fingermark detection research has considerably increased over the last decade. However, whilst the number of publications utilising scales has increased, it is not proportional to the number of papers using the IFRG scales. The choice of scale is often institution specific and even more specific to their location. There are also numerous different adaptations of the IFRG recommended scales, as well as novel scales, which do not associate with the IFRG recommended versions being introduced the more research continues to grow. One such reason for this is investigated here, as different quality parameters are utilised within each individual scale. There is underrepresentation of these quality parameters within some of the IFRG scales, in particular the Centre for Applied Science and Technology (CAST) scale. This correlates to the considerable number of tailored approaches as authors are forced to add these parameters within the descriptions. Until there is an introduction of clear guidelines surrounding all areas of fingermark quality, from definition to parameters chosen within phases, the research area will continue to face such issues. This article recommends areas of potential study, whilst also recommending procedures that may be employed to alleviate some of the issues seen with fingermark quality evaluation.

Biodegradable plastics and their impact on fingermark detection methods

The use of plastics is extremely prevalent in society, with most individuals likely to handle several plastic items per day. It is therefore not surprising that many exhibits recovered from the scene of a crime are plastics, which are processed and examined for traces such as fingermarks. Societal trends have been pushing towards more environmentally friendly products with alternatives to traditional disposable plastics becoming increasingly available. These alternate plastics have different chemical compositions and physical properties, which may impact fingermark development for these substrates. As most detection techniques are known to be substrate-dependent, it is crucial to review current methods and procedures to examine how effective they are on new materials. The aim of this research was to assess a range of fingermark detection techniques on biodegradable plastics and provide recommendations for the preferred technique. First, the prevalence of these materials in the Australian market was evaluated. Over 40 different plastics obtained within the Sydney area were then divided into six broad categories using consumer information in combination with ATR-FTIR spectroscopy analysis. Following this, selected plastics from each category were used as substrates for the fingermark development study. In total, 6480 fingermark specimens were collected as split marks, to form 2160 fingermark comparisons. Each substrate was then developed with four fingermark detection techniques suitable for plastic substrates: cyanoacrylate (CA) fuming, vacuum metal deposition (VMD), powder suspensions (PS), and single metal deposition (SMD). SMD resulted in the most consistent development method across all tested substrates. VMD was able to successfully develop fingermarks on polyethylene-based plastics, but led to poorer results on alternative plastics, while CA fuming and PS were notably more dependent on the surface texture. This research was successful in confirming that biodegradable plastics do in fact have an impact on fingermark development techniques commonly applied on traditional plastics and recommendations have been formed to aid in operational contexts to improve the potential to recover latent fingermarks from biodegradable plastics.

Greasy fingermark detection on porous surfaces using Oil red O in a gas phase: Comparison with Oil red O in solution

Oil Red O is a fingermark reagent that is useful for developing greasy fingermarks. Classic Oil Red O formulation is based on methanol-water solution. The use of solvent can be harmful to the forensic practitioner and the environment. Moreover, solvent can destroy hand writing and biological traces. In this paper a new solvent-free Oil red O deposition method have been proposed. Experimental method is based on Oil Red O deposition from a gas phase in reduced pressure conditions. 1728 split, greasy fingermarks deposited on paper have been developed with the new method and a benchmark one. The development results have been compared. The general performance of the new method has been found inferior to the solvent based formulation. However, in most cases both methods were comparable. This shows that the experimental method could be a possible alternative to the classic one in the cases where drawbacks connected to the solvent use are unacceptable. Even though, presented results are promising, more research and optimization is necessary, before the new method can be included into the forensic expert toolbox.

Fingermark detection using upconverting nanoparticles and comparison with cyanoacrylate fuming

This paper reports the synthesis of high-quality upconverting nanoparticles (UCNPs) - sodium yttrium tetrafluoride doped with ytterbium and erbium (NaYF4:Yb,Er) with a silica shell and capped with phenyl functional groups. The main goal of this research was to design tailor-made UCNPs for fingermark detection, to test and validate a nanoparticle-based detection technique and to compare their performance against a benchmark method to assess potential implementation in routine practice by law enforcement agencies. The water-based UCNPs solution was applied to natural fingermarks on a number of substrates. This is the first ever systematic comparative study between UCNPs and a benchmark fingermark detection technique - cyanoacrylate fuming (CAF) followed by luminescent dye staining. Fingermark detection effectiveness was studied by treating 300 latent fingermark specimens on aluminium foil, polyethylene, polypropylene and glass slides. It was concluded that, on average, CAF performed better across the substrates tested. Nevertheless, UCNPs can be advantageous for fingermark detection on multicoloured, patterned or luminescent substrates due to their unique optical properties. There are, however, shortfalls associated with their synthesis and use that need to be addressed before they can be considered for operational purposes.