Quote from Lieutenant Disher in Mr. Monk Goes to Group Therapy
Adrian Monk: Where's the towel? There's no towel next to the pool. I wouldn't go swimming first thing in the morning in October without a towel. I mean, I wouldn't go swimming anyway, but you see what I mean. I think she was killed.
Lieutenant Disher: Let me guess. The victim was not afraid of water. It's him, The Opposite Killer. That's his M.O.
Captain Stottlemeyer: There is no Opposite Killer. If there were, you would have been killed by a falling rocket scientist years ago.