Publication details
Comparative analysis of trace DNA samples for STR typing at the crime scene and from material traces in the forensic laboratory
| Authors | |
|---|---|
| Year of publication | 2026 |
| Type | Article in Periodical |
| Magazine / Source | Forensic Sceence Research |
| MU Faculty or unit | |
| Citation | |
| Doi | https://doi.org/10.3788/tfsr20250221 |
| Keywords | touch DNA; transfer DNA; trace DNA; tDNA; tDNA sampling; DNA profiling; STR profiling; DNA swabbing; fingerprint |
| Description | Touch DNA, also known as transfer DNA or trace DNA (tDNA), is becoming an integral part of forensic investigations. tDNA is often the only genetic material recovered from a crime scene, as biological material is often missing. The analysis of tDNA is complicated by several major issues that need to be addressed: low quantity, poor quality of the molecule, high risk of contamination, and mixing of DNA profiles. Evidence obtained from tDNA analysis is often considered unreliable, so the forensic protocol should address and overcome the main problems and maximise the usability of the evidence in legal proceedings. This study evaluates the effectiveness of Crime Scene Samples (CSS) and Forensic Laboratory Samples (FLS) for STR typing using the Fisher´s exact text. CSS samples were collected at the crime scene by swabbing sites and objects, while the second type of sample was obtained by a forensic geneticist under laboratory conditions from material traces seized at the crime scene. The samples were taken from actual cases investigated by the police of the Czech Republic. The results, analysed using the R software, showed that 56.2% of the tDNA samples could provide STR profiling results of the same quality as samples with proven presence of biological material (semen, saliva and blood). The study demonstrated that tDNA sampling is practical and that DNA profiles generated from tDNA samples have the potential to identify survivors at the individual identification level. The study highlighted the need for refinement and development of new techniques to determine the amount of biological tDNA material in the traces of the crime scene and also in the examination of the material traces in the forensic laboratory, as this direction is desirable given the number of traces examined compared to the other biological materials mentioned above. |