Biological traces at the crime scene

Abstract

Biological traces found at the crime scene are of human, animal and plant origin. Among them the most commonly present are of human origin - hair, blood, sperm, saliva, sweat and tears, but also nails, teeth and bone bits. When considering biological traces as evidence, we distinguish incontestable and debatable traces. Incontestable samples are taken from suspects, alive victims and from all other people that may have been in contact with the traces or objects at the crime scene. Debatable traces are found at the scene of events, on objects or people associated with the venue or criminal offence, whose identity and role in the event is known. When taking biological traces, it is necessary to comply with the anti-contamination and safety rules regarding handling with biological material, including self-protection measures. The goal of processing biological traces that are usable as court evidence is to provide a sufficient amount of DNA, which can be used in the individualization of each biological trace. However, in addition to this analytical step by which evidence is undoubtedly drawn from the trace, biological traces can be treated with some simpler, cheaper and less reliable methods. In this review article, we also discussed the judicial significance of sperm traces. Sperm is often analyzed for crimes impinging on sexual freedom. Hair samples can be used for toxicological analysis and to connect perpetrators to an event or victim.