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Characterization of challenging forensic DNA traces using advanced molecular technologies
Amel Larnane1,2, Caroline Lefèvre-Horgues3, Corinne Cruaud4
1Institut de Recherche Criminelle de La Gendarmerie Nationale (IRCGN), 95000, Cergy-Pontoise, France. alarnane@cnrgh.fr.
International Journal of Legal Medicine
|February 28, 2025
Summary
Forensic DNA analysis struggles with low-quality samples. New methods using ultra-sensitive electrophoresis and sequencing reveal non-human DNA in crime scene traces, improving sample characterization.
Area of Science:
- Forensic Science
- Molecular Biology
- Genetics
Background:
- Crime scene DNA is often scarce or degraded, challenging conventional short tandem repeat (STR) profiling.
- Existing forensic technologies are limited by DNA quantity and quality, hindering suspect or victim identification.
Purpose of the Study:
- To evaluate advanced technologies for characterizing challenging forensic DNA traces.
- To improve the analysis of low-quality and low-quantity DNA samples from crime scenes.
Main Methods:
- Ultra-sensitive pulse-field electrophoresis (FPS) for DNA visualization.
- Real-time quantitative PCR (qPCR) using Alu repeats for human DNA quantification and integrity analysis.
- 16S ribosomal RNA (rRNA) gene amplicon sequencing for microbiota identification.
Main Results:
- FPS analysis revealed differences in casework samples compared to model traces, indicating non-human DNA presence.
- Human DNA was found in 84% of traces (avg. 70 pg).
- Microbial DNA was identified as the most abundant DNA type in forensic traces via 16S rRNA sequencing.
Conclusions:
- Advanced techniques offer new insights into the composition of forensic traces.
- Characterizing human and non-human DNA improves the sorting and profiling of challenging forensic samples.
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