S05:E07 - Trail of Truth

Nancy Newman and her two young daughters are found brutally murdered and sexually violated in their Anchorage, AK home. Investigators cannot find a conclusive link to their prime suspect. To solve the puzzle, an FBI analyst designs an unique experiment, in which pubic hairs found at the scene are used to establish not only that Kirby Anthoney was in the home, but that he was there when the crime was committed.