Most of us don't think watching a 12-year-old girl strangle to death is a sexual turn-on, but to him it is.
We don't really understand these serial sexual homicides to the extent that we think we do. We think we know what's going on. But because these people are so rare, we really don't. It's chilling.
It's a very lethal combination. A normal male his age may lead a normal life and have sexual fantasies.