Inferring the presence of spermatozoa in forensic samples based on male DNA fractionation following differential extraction

We further demonstrate that, if the same male DNA profile is represented more prominently in the sperm fraction versus the epithelial fraction, the analyst should not fall into the intuitive trap of inferring the presence of spermatozoa in the sample. Instead, enrichment calculations must be based on the measured quantity of male and total DNA in each fraction and not the male:female DNA ratios observed in the DNA profiles.