Variability associated with interpreting drugs within forensic hair analysis: A three-stage interpretation.

Hair analysis is capable of determining both an individual's long-term drug history and a single exposure to a drug, which can be particularly important for corroborating incidents of drug-facilitated crimes. As a source of forensic evidence that may be used in a court of law, it must be credible, impartial and reliable, yet the pathways of drug and metabolite entry into hair are still uncertain. Many variables may influence drug analysis results, most of which are outside of the control of an analyst. An individual's pharmacokinetic and metabolic responses, hair growth rates, drug incorporation routes, axial migration, ethnicity, age and gender, for example, all display interpersonal variability. At present there is little standardization of the analytical processes involved with hair analysis. Both false positives and negative results for drugs are frequently encountered, regardless of whether a person has consumed a drug or not. In this regard, we have categorized these variables and proposed a three-stage analytical approach to facilitate forensic toxicologists, hair analysis experts, judiciaries and service users in the analytical and interpretation process.

Partnership between academics and practitioners - Addressing the challenges in forensic science.

This research discusses the development of academic-practitioner partnerships in forensic science and examines the opinions and experience of those involved in the field. An anonymous online survey was completed by 56 participants who work in the field of forensic science. The questions related to their work experience, their experience of research and partnership, and their opinions on the benefits and barriers that exist. The results were analysed using a mixed methods approach, with quantitative analysis of the responses to closed questions using two-way chi-square statistical analysis, and qualitative analysis of the free text responses using reflexive thematic analysis. This work identifies the demand for partnership, the perceived benefits and barriers that exist, and establishes how the role of the participant (academic, pracademic or practitioner) impacts their view of partnership. We include the term pracademic to mean an individual who has worked as a practitioner and an academic, not necessarily simultaneously. Quantitative analysis identified that there was very little statistically significant difference in the responses between groups. Pracademics considered that 'institutional and cultural' and 'lack of the respect of the other role' were more significant barriers than the other groups. Association was also found between those with greater experience of research and the view that partnership 'improved legitimacy in practice' and 'increased legitimacy of research'. There was also statistical significance in those with more than average experience of partnership who identified 'improved legitimacy in practice' as a benefit of partnership. Reflexive thematic analysis of free text comments identified a need and demand for partnership with three key themes developed as being necessary for successful partnership. These are the 'three 'R's' - the need for effective communication and the development of a Relationship; the Relevance of the partnership to the participants role; and the inclusion of personal Reward such as improved practice or better research.

Vacuum metal deposition enhancement of friction ridge detail on ballistic materials.

The efficacy of Gold/Zinc and Silver/Zinc vacuum metal deposition (VMD) protocols were assessed as stand-alone methods of fingermark enhancement on ballistic brass materials. The results demonstrate the effectiveness of VMD enhancement on a large pool of donors (n = 20), with potentially identifiable marks recovered for the majority of donors, including samples aged up to two months. Of the 20 donors a subset of six donors were selected to assess the capability of VMD enhancement on brass fired cartridge cases, from which some friction ridge detail (FRD) was recovered. Lastly, an attempt to understand which fingermark components are facilitators of VMD enhancement was made. Fingermark residue was extracted from brass tiles and fired cartridge cases before analysing chromatographically (GC-MS). Although some key components were indicated, further evaluation of all fingermark components is needed to draw firm conclusions as to the role each plays in VMD enhancement.

A Preliminary Study on Vacuum Metal Deposition as a Standalone Method for Enhancement of Fingermarks on Ballistic Brass Materials.

In order to assess the efficacy of vacuum metal deposition (VMD) as a technique to develop fingermarks on ballistic metallic surfaces, a preliminary study using six donors (three male & three female) was conducted. Using a sequential metal deposition process, two metal combinations were studied-gold/zinc and silver/zinc. Results indicate the potential of this technique, by developing identifiable fingermarks on brass metal disks aged from a few days up to more than a month old. As the development of fingermarks on fired (brass) cartridge cases is an area of interest, a further study was conducted where a total of 20 fingermarks were deposited on cases. After firing, second level fingermark characteristics were successfully observed on cartridge cases highlighting its potential as a fingermark enhancement method for ballistic brass materials. Further work is required to fully evaluate the VMD process and its reliability as a fingermark enhancing method on ballistic surfaces.

Detection of Fingermarks-Applicability to Metallic Surfaces: A Literature Review.

There are many different fingermark visualization techniques available, and the choice of methodology employed may be dependent on the surface type. This comprehensive review of the scientific literature evaluates the methodologies of fingermark enhancement methods that are applicable to metallic surfaces; optical, physical, chemical, and physicochemical methods are critically discussed. Methods that are currently used and those that have the potential to reduce the cost and time required to process evidence and increase the recovery rates are considered and are assessed against the Centre for Applied Science and Technology (CAST) and the International Fingerprint Research Group (IFRG) guidelines. The use of chemical imaging techniques in particular has increased the potential to recover fingermarks of sufficient quality for identification purposes. Presently, there appears to be a lack of detailed research pertaining to validation and thorough casework studies for fingermark enhancement techniques. Further studies incorporating these guidelines are recommended.