From frequented environments to the crime scene: Evaluating findings of fibre comparisons in complex transfer scenarios.

The evaluation of the results from a fibre comparison given activity level propositions is well established when considering only a single group of potential primary transfers. However, secondary transfers are less prevalent in the literature despite their potential value, especially in cases where the primary transfers are not sufficiently informative. In particular, one can consider the fibres from frequented environments of the person of interest (POI) identified in a struggle.

Interpretation of a paint cross-transfer on a burglary scene - A case report.

In forensic paint examination, paint traces retrieved on a crime scene are regularly compared to painted objects seized from a suspect. Less often, traces are only observed on the seized objects and compared to a damaged painted object on the crime scene. In some specific cases, paint traces may be found both on the crime scene and on one or multiple seized painted objects.

Fibres in the nasal cavity: A pilot study of the recovery, background, and transfer in smothering scenarios.

In cases where the suspected cause of death is smothering, fibre traces recovered from the nasal cavity are hypothesised to refute or support this proposition. In order to carry out such evaluations, an efficient recovery method must first be established. This pilot study tested five different recovery methods on 3D printed models of nasal cavities.

On the impact of DNA extraction procedure on the recovery of condom evidence.

On the international level, different protocols exist for sampling condom traces, similarly to DNA traces. Usually collected with cotton swabs, some protocols use nylon swabs, which were found more efficient for the desorption of DNA, because they offer a better desorption of the compounds during the extraction. In addition, not all the protocols do contain swabs for other evidence than DNA.

A probabilistic approach towards source level inquiries for forensic soil examination based on mineral counts.

Forensic soil examination has a well-established foundation in forensic science, this is in part due to the widely varied and complex nature of soil. Within this domain, mineral suite studies are a commonly utilized tool in soil examination. However, statistical or probabilistic approaches towards the interpretation of results from such analysis are lacking and this study aims to fill that gap.

A preliminary investigation of transfer of condom lubricants in the vaginal matrix.

Condom evidence has become in the past years a very relevant item of evidence in sexual assault or rape cases, being an objective help in the reconstruction of the activity. Traces recovered from a vaginal swab might help to identify whether a condom or other lubricants were used, and thereby possibly confirming or infirming allegations of the parties. However, the interpretation of condom traces can be challenging and requires a detailed understanding of various factors like condom lubricant chemical composition and occurrence on the market, transfer and persistence parameters and background.

The use of an optimized DRIFTS-FTIR method for the forensic analysis and classification of silicone condom lubricants.

Condom residues may be encountered in forensic investigations as traces left in sexual assault or rape cases. Considering casework samples analysis, where material from swabs will need to be extracted, Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) was reported as the most relevant method for trace evidence analysis. However, there has been no study to identify which specific parameters were the most suitable for the analysis of silicone-based lubricants, especially in terms of repeatability of the analyses.

Condom evidence: Characterisation, discrimination and classification of pyrolysis-GC-MS profiles.

Analysis of condom evidence commonly focusses on the detection of silicone-based lubricants, such as polydimethylsiloxane (PDMS). Although various instruments are used to analyse silicone lubricants, pyrolysis-gas chromatography coupled to mass spectrometry (py-GC-MS) is one of the few instruments that presents immediate applicability to casework. However, considering that this technique detects silicone-based evidence, it is important to evaluate the discrimination potential of the method when applied to various samples.

A forensic international market survey of condom lubricants and personal hygiene products using ATR-FTIR coupled to chemometrics.

Condom residues may be encountered in forensic investigations as traces in sexual assault or rape cases. Casework studies have shown the value of distinguishing condom residues from other types of personal products used by women. However, up to now, there has been no investigation of their chemical variability within an international context.

Analysis of condom evidence in forensic science: Background survey of the human vaginal matrix using DRIFTS and pyrolysis-GC/MS.

Condom traces are increasingly detected from victims of sexual assault, mostly from vaginal swabs. Protocols have been developed for the analysis of silicone-based condom lubricants using DRIFTS-FTIR and py-GC/MS, but very little research is concerned with the background contribution of the vaginal matrix itself. The present contribution would be an asset for more fundamental research on condom residues in the vaginal matrix, as well as for interpretative purposes in the forensic area.

Fibre persistence on static textiles under outdoor conditions.

The persistence of fibres under outdoor conditions is seldom investigated. This research aimed to study simultaneously the influence of several factors (and their cross-interactions) on the persistence of fibres on static textile surfaces. In order to achieve this aim, a design of experiments was successfully implemented under laboratory conditions.

Characterization and classification of water-based compounds in condoms and personal hygiene products using GC-MS.

Analysis of condom evidence commonly focusses on the detection of silicone-based lubricants, such as polydimethylsiloxane. However, water-based compounds such as propylene glycol or glycerin can also be used as condom lubricants and may, therefore, be detected as transferred traces. Evaluation of the variability amongst a large sample set from an international market is needed to determine what are the most likely compounds that may be detected in casework.

Forensic analysis of condom traces: Chemical considerations and review of the literature.

The analysis of condom traces has recently been added to the standard forensic examination protocol of sexual assault and rape cases. Several recent studies have thus focussed on the detection of condom components and classification of the chemical profiles using statistics, obtaining very promising results. The purpose of the present article is to critically review the literature regarding condom chemical analysis.

The evaluation of evidence for microspectrophotometry data using functional data analysis.

Microspectrophotometry data arise in the study of many forensically applicable situations. The situations here are those of ink and fibres. In a criminal investigation, data associated with a crime scene are compared with data associated with a person of interest.

Identification of some factors influencing soil transfer on shoes.

In criminal activities, soil can be transferred from a crime scene to items linked with a perpetrator; for example, shoes, cars or tools. Several parameters will influence the quantity of soil transferred in a given scenario. The knowledge of the most influential factors can help the expert to assess the evidence using a logical approach at the activity level or to predict the amount of soil that can be expected in a given scenario.

Pre-analytical considerations of condom traces: A review of composition, background, transfer and persistence.

Today, rape and sexual assault cases are mainly solved using evidence such as medical evidence or DNA analysis. Condom traces have been found to be present in 10% of assaulted women, when no DNA is found [1]. Numerous studies have emphasized the interest of analysing the composition of male condoms and their traces, and developing specific methods for the analysis of this type of evidence.

A study of background population of fibres on knife blades.

Edged weapons are frequently used to commit violent crimes (e.g., homicides, assaults or sequestrations).

A preliminary investigation of textile fibers in smothering scenarios and alternative legitimate activities.

Was this group of target fibers transferred during a criminal action? Is it possible that it was transferred during another legitimate activity? Acquiring knowledge about the activity, whether legitimate or criminal, leading to the transfer of a group of fibers is a recurring challenge encountered throughout the evidence interpretation process. Trace evidence such as fibers may assist with generating a reasoning of the activity which produced the trace, but this assumes that one already has a thorough understanding of the transfer phenomenon. How to generate and then use such relevant knowledge? What are the influencing parameters and which ones should (or can) be controlled? The present work focuses on homicides by smothering using a pillow and the transfer of fibers on the face of the victim in such events.

Discussion on how to implement a verbal scale in a forensic laboratory: Benefits, pitfalls and suggestions to avoid misunderstandings.

In a recently published guideline for evaluative reporting in forensic science, the European Network of Forensic Science Institutes (ENFSI) recommended the use of the likelihood ratio for the measurement of the value of forensic results. As a device to communicate the probative value of the results, the ENFSI guideline mentions the possibility to define and use a verbal scale, which should be unified within a forensic institution. This paper summarizes discussions held between scientists of our institution to develop and implement such a verbal scale.

Combining spectroscopic data in the forensic analysis of paint: Application of a multiblock technique as chemometric tool.

A study (Muehlethaler et al. [9]) has demonstrated the application of chemometrics for the analysis of domestic red paints. The paints have been analyzed with IR and Raman spectroscopies.

Evaluation of infrared spectra analyses using a likelihood ratio approach: A practical example of spray paint examination.

Depending on the forensic disciplines and on the analytical techniques used, Bayesian methods of evaluation have been applied both as a two-step approach (first comparison, then evaluation) and as a continuous approach (comparison and evaluation in one step). However in order to use the continuous approach, the measurements have to be reliably summarized as a numerical value linked to the property of interest, which occurrence can be determined (e.g.

Forensic aspects of the weathering and ageing of spray paints.

This paper presents a preliminary study on the degradation of spray paint samples, illustrated by Optical, FTIR and Raman measurements. As opposed to automotive paints which are specifically designed for improved outdoor exposure and protected using hindered amine light absorbers (HALS) and ultra-violet absorbers (UVA), the spray paints on their side are much simpler in composition and very likely to suffer more from joint effects of solar radiation, temperature and humidity. Six different spray paint were exposed to outdoor UV-radiation for a total period of three months and both FTIR and Raman measurements were taken systematically during this time.

Motorcycle helmets: What about their coating?

In traffic accidents involving motorcycles, paint traces can be transferred from the rider's helmet or smeared onto its surface. These traces are usually in the form of chips or smears and are frequently collected for comparison purposes. This research investigates the physical and chemical characteristics of the coatings found on motorcycles helmets.

The analysis of colored acrylic, cotton, and wool textile fibers using micro-Raman spectroscopy. Part 2: comparison with the traditional methods of fiber examination.

In the second part of this survey, the ability of micro-Raman spectroscopy to discriminate 180 fiber samples of blue, black, and red cottons, wools, and acrylics was compared to that gathered with the traditional methods for the examination of textile fibers in a forensic context (including light microscopy methods, UV-vis microspectrophotometry and thin-layer chromatography). This study shows that the Raman technique plays a complementary and useful role to obtain further discriminations after the application of light microscopy methods and UV-vis microspectrophotometry and assure the nondestructive nature of the analytical sequence. These additional discriminations were observed despite the lower discriminating powers of Raman data considered individually, compared to those of light microscopy and UV-vis MSP.