" Because this devil is definitely an older man, probably foreign. The FBI would classify him as a type IV killer, the worst kind and difficult to catch. A type IV serial killer has no remorse, doesn’t understand the concept. He has what they call an anger-excitation profile. The whole process he performs is his own way to sexual gratification. This man kills for sport. He’s not out of control, quite the opposite in fact. Most importantly, in regard to your daughter’s safety, the rules of his game are that he must murder strangers. He doesn’t kill people he knows. So if your daughter’s with people she knows then she cannot be with the killer. "

― Harlan Wolff , Bangkok Rules