Evaluation of Raman spectroscopy for the analysis of colored fibers: a collaborative study

A collaborative study on Raman spectroscopy was carried out by members of the ENFSI (European Network of Forensic Science Institutes) European Fibres Group (EFG) on three dyed fibers: two red acrylics and one red wool. Raman instruments from six different manufacturers were tested as well as nine different laser wavelengths ranging from blue (lambda = 458 nm) to near infrared-NIR (lambda = 1064 nm). This represents the largest comparison study of Raman analytical parameters carried out on identical fiber samples. For the chosen fiber and dye samples, red lasers (lambda = 633 and 685 nm) gave the poorest spectral quality whereas blue (458 nm), green (514 nm) and near infrared lasers (785, 830 and 1064 nm) provided average results. Blue (488 nm) and green lasers (532 nm) globally gave the best quality spectra. Fluorescence problems were often encountered with some of the excitation wavelengths and therefore a flexible Raman instrument equipped with different lasers can be recommended to measure forensic fiber samples. The instrument should also be equipped with a Raman microscope in order to be able to focus on a single fiber. This study shows that Raman spectroscopy usually enables the identification of the main dye present in a colored fiber; however, minor dye components are much more difficult to detect. SERRS (Surface Enhanced Resonance Raman Scattering) techniques give an improvement of the dye's spectral intensity but no spectral improvement was observed for the two red acrylic and red wool fibers tested.     

Methodological development: structured outcome assessment and community risk monitoring (SORM)

This paper describes an effort to develop a clinical tool for the continuous monitoring of risk for violence in forensic mental health clients who have left their institutions and who are dwelling in the community on a conditional release basis. The model is called Structured Outcome Assessment and Community Risk Monitoring (SORM). The SORM consists of 30 dynamic factors and each factor in SORM is assessed in two ways: The current absence, presence or partial och intermittent presence of the factors, which is an actuarial (systematized and 'objective') assessment. Secondly, the risk effect, i.e. whether the presence/absence of factors currently increases, decreases or is perceived as unrelated to violence risk, is a clinical (or impressionistic) assessment. Thus, the factors considered via the SORM can be coded as risk factors or protective factors (or as factors unimportant to risk of violence) depending on circumstances that apply in the individual case. Further, the SORM has a built-in module for gathering idiographical information about risk-affecting contextual factors. The use of the SORM and its potential as a risk monitoring instrument is illustrated via preliminary data and case vignettes from an ongoing multicenter project. In this research project, patients leaving any of the 9 participating forensic hospitals in Sweden is assessed at release on a variety of static background factors, and the SORM is then administered every 30 days for 2 years.     

Survey of crowbar and household paints in burglary cases-population studies, transfer and interpretation

Experimental data useful for the interpretation of paint evidence recovered during burglary cases were obtained. A population study was carried out on 41 blue crowbars seized on suspects in Switzerland and 37 blue paints traces found at burglary scenes. Paint traces were also searched on the blades of 207 crowbars seized by the police in Switzerland and 24 white traces were analysed: these paints were analysed using infrared spectroscopy (FTIR) in order to estimate relative frequencies of each paint type. Simulated contacts were carried out between crowbars and painted wood in order to study the phenomenon of transfer and to evaluate the amount of paint transferred: a total of 198 simulations were carried out including individual, successive and cross transfer. The paint properties such as the chemical composition and its age influenced the amount of paint transferred. Cross transfer from the tool paint to the wood and vice versa was regularly observed. Moreover, secondary transfer of paint coming from the preceding wooden surfaces was also systematically observed: this could establish links between several burglary scenes and a suspected tool. A scenario of a burglary case involving the cross transfer between tool and household paints is proposed as a numerical example: the evaluation of such case was formalised using likelihood ratios based on the experimental data obtained.