Enhancing forensic casework interpretation through DNA methylation-based analysis: A case study of pooled blood...

Area of Science:

• Forensic Science
• Genetics
• Epigenetics

Background:

• Investigating unidentified biological material is crucial in forensic casework.
• Integrated genetic and epigenetic profiling aids in reconstructing incident scenarios and assessing criminal involvement.
• DNA methylation analysis can determine cellular composition, donor age, and smoking status.

Purpose of the Study:

• To profile an unknown donor from a complex forensic case involving pooled blood.
• To reconstruct incident circumstances using integrated genetic and epigenetic analyses.
• To demonstrate the utility of advanced profiling techniques in challenging forensic investigations.

Main Methods:

• Short tandem repeat (STR) typing and Y-haplotyping for genetic profiling.
• SNaPshot analysis for body fluid identification.
• Array-based DNA methylation profiling for cell/tissue deconvolution, age, and smoking status estimation.

Main Results:

• Two scene samples originated from the same Korean male donor (Y-haplogroup O3a2).
• The presumed blood sample was a blood-saliva mixture with whole blood and upper gastrointestinal tissue components.
• Analysis supported hematemesis, indicating a medical scenario rather than criminal activity; donor age estimated at 50-60 years, current smoker.

Conclusions:

• Integrated genetic and epigenetic profiling, especially tissue-of-origin analysis, generates crucial investigative leads.
• These methodologies facilitate the inference of incident circumstances, even with suboptimal sample quality.
• The study showcases the power of advanced forensic techniques in complex casework and donor identification.