S6, E9: A woman who is paralyzed from the waist down was sexually assaulted, and hours later a woman with an infant who lives upstairs suffers the same fate. The cops want to catch this guy, quickly. The search becomes even more urgent when a woman who was on crutches, shows up at the emergency room (beaten, but not raped), most likely a victim of the same perp. They are able to compile a very basic sketch (it looks like the Unabomber) and have no luck getting a hit on the blood found on the woman's crutch.