The invention generally relates to methods and kits for capturing sperm nucleic acids from or in a biological sample. In one embodiment the method the method includes, contacting the sample with a lysis solution, having a protamine-DNA complex, to lyse the cell and applying a protamine-specific antibody. This results in the protamine-specific antibody binding to the protamine-DNA to form a complex which may be captured, purified, or detected. Also provided are kits for carrying out the disclosed methods.