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Published on: March 9, 2015
DNA typing from vaginal smear slides in suspected rape cases
Dayse Aparecida da Silva1, Andréa Carla de Souza Góes, Jorge José de Carvalho
1DNA Diagnostic Laboratory, Biology Institute, Universidade Estadual do Rio de Janeiro, Rio de Janeiro, Brazil.
Sao Paulo Medical Journal = Revista Paulista De Medicina
|July 17, 2004
Summary
DNA typing from vaginal smear slides successfully identified a suspect in two rape cases. This forensic technique provided strong evidence, proving it 3.3 billion times more likely the suspect was the offender.
Area of Science:
- Forensic Science
- Genetics
- Molecular Biology
Background:
- Sexual assault investigations require proof of penetration.
- Forensic medical services collect detailed physical evidence, including vaginal swabs.
- Biological material from swabs is often preserved on glass slides.
Observation:
- Two rape cases in Rio de Janeiro involved victims identifying a suspect who denied involvement.
- Vaginal smear slides, collected three months post-assault, were the primary forensic evidence.
- Modified DNA extraction protocols were developed for biological material fixed on glass slides.
Findings:
- DNA typing was successfully performed on epithelial and sperm cells recovered from vaginal smear slides.
- Analysis utilized nine short tandem repeat (STR) loci for human identification.
- The results indicated a 3.3 billion times higher probability that the suspect deposited the sperm cells compared to any other individual in the population.
Implications:
- DNA analysis from vaginal smear slides is a viable and powerful forensic tool.
- This method can provide conclusive evidence in sexual assault cases, even with delayed analysis.
- The study highlights the importance of preserving biological evidence for advanced DNA profiling.
