It was probably his eyes. Psychopaths have no soul in their eyes.
A lot of murderers have soulless eyes. Charles Manson is utterly creepy, too, for the same reason.
Not all psychopaths are murderers, or even criminals. But they all seem to have those empty eyes.
You’re both right. It’s the same with the eyes of the Manson women, of Tex Watson, all of them are so empty and there’s something about them that is just dead. Drained out. It’s the only way to explain WHY people who don’t have any reason to realistically kill someone. It’s the same instinct healthy people have over people who seem normal, but end up showing themselves to be maniacs later on.