The sexing of bloodstains by testosterone: total protein ratio determination.

A simple method for the extraction of testosterone from bloodstains followed by its measurement by radioimmunoassay is described. Complete discrimination of males and females was achieved with measured bloodstains as small as 40 microliters. With stains of unknown volume the total protein content of the stain was determined as an internal reference level. Using the testosterone/protein ratio unequivocal identification was possible for 75% of the stains from males and 50% from females.