Forensic biological examination is a part of forensic science, which has the aims of identify biological stains on findings. It is important for the identification of even the smallest biological stains and for prevent the contaminations phenomena during the forensic analysis. In addition, it is important to highlight the crucial position forensic biology has in preliminary investigation, whose compromise lead to loss of more specific analysis, including genetics.
In order to improve the efficiency of stain-identification, forensic laboratories are common to use different technologies, such as alternative light sources (ALS). The ALS are forensic lights, non-laser, designed with a white light source and equipped with a range of filters that allow to select the emitted radiation; the biological evidence, due to their characteristics, can react to this different wavelength light with absorbance signal or fluorescence signal.
During a forensic inspection of biological stain on findings, the results of these technical analyses could be affected by the presence of artifacts. Unfortunately, in the area of forensic biology examination, artifacts are not well defined and described.
The idea of artifacts presence in forensic biology examination is well known by the operators, although there are few studies about these phenomena. The artifacts, in forensic biology examination are different signal phenomena of absorbance and fluorescence not assigned to biological stains, but caused by the fabric’s composition.
According to the study of D’Orio, E. et al. (2022) has been possible to identify two different types of artifacts on fabrics:
|The first type, identified in the study as a letter “A”: has been named “Brightling”||The second type of artifact, identified in the study as a letter “B”: has been called “Shadowling”|
|Is a fluorescence signal, normally of small size and brightly colored||Is a dark and absorbance signal of larger size|
The aim of that study was to define and describe for the first time the presence of artifacts in the forensic biological examination analysis.
The presence of artifacts on the fabrics is not visible with naked eye, in fact, it is necessary use the Alternative Light Sources (ALS).
380nm highlights better the Shadowling type artifact, instead the ALS 450nm highlights better the Brightling type artifact.
Thus, the presence or the absence of artifacts depend of the textile typology of fabrics.
Actually, synthetic fabric has the less number of artifacts, while cotton has the biggest number.
In cotton and wool Brightlings are more present, while in jeans and synthetic Shadowlings are more present.
In the scientific literature there are few studies about this topic, and for this reason, it seems clear the necessity to highlight these phenomena to prevent false positives occurring in forensic biological examination and to highlight the impact of artifacts in forensic biology examination. More studies concerning these phenomena are important to improve the preliminary biological examination and ensure a better basis for more specific analyses, aimed at attributing specific traces or samples to unique suspect.
D’Orio, E., Czerwińska, K., Lucanto, C., Calabrese, G., Montagna, P. (2022). Evaluation of the Presence of Artifacts in the Forensic Biological Examination. 11th annual forensics science symposium, Florida International University
Forensic Biology – Georgia Bureau of Investigation Division of Forensic Sciences
Ms. Chiara Lucanto
Master Degree in Forensic Biology at University of Calabria – Italy
PG Researcher at Bio Forensics Research Center
Certified Specialist of “Forensic Biology Survey” – Accredited by FAC CERTIFICA (according to ISO 17024 STANDARDS)
Mr. Giuseppe Calabrese
Master Degree in Evolutionistic Biology, Ecology and Applicate Anthropology at University of Rome Tor Vergata – Italy Researcher at Bio Forensics Research Center