Progress in sperm cell separation and analytical techniques for semen-epithelial mixed stains: a forensic perspective

Area of Science:

• Forensic Science
• Genetics
• Molecular Biology

Background:

• Sperm-epithelial cell mixture analysis is crucial for sexual assault investigations, providing vital DNA evidence.
• Traditional methods face challenges with trace, degraded, or low-concentration samples.

Purpose of the Study:

• To comprehensively review innovative methods for isolating and analyzing spermatozoa and epithelial cells.
• To guide forensic practitioners in selecting appropriate techniques for complex casework.

Main Methods:

• Evaluation of diverse separation techniques: differential extraction, filtration, micro-capture, optical tweezers, microfluidics, flow cytometry, and immunomagnetic beads.
• Analysis of methods at both cellular and molecular levels.

Main Results:

• Each technique offers unique strengths (e.g., microfluidic precision, immunomagnetic cost-effectiveness) and limitations.
• No single method is universally optimal; selection depends on case-specific factors.

Conclusions:

• Tailored approaches are essential for complex forensic cases involving sperm-epithelial mixtures.
• Novel techniques enhance accuracy and efficiency in forensic DNA analysis, potentially reducing backlogs and improving justice outcomes.