CSI: NY Season 7 Episode 15 (02/18/11)
A serial rapist was found murdered in the exact way he had attacked his victims. The CSIs suspected that a vigilante was taking matters into his own hands because of a 911 call that foretold the killing. Evidence showed that the vigilante might have been a woman. At first the rapist's first victim, Kate Price, was suspected because of photos found in her possession and DNA found on the body.
Further investigation and the murder of another sexual offender meeting the same M.O. led the CSI's to another woman who was in Kate Price's support group. Kate eventually confessed that she had talked to members of her group about seeing her rapist on the street and taking photos of him. One of the women, and Kate's lawyer took the information and decided to take matters into their own hands to gain justice that the law did not grant.