This is just idle morbid curiosity, not a real thing I've been told.

Say one night he confesses to you that he was waiting for a train late one night when there was only one other person at the station, and he got to wondering what it would be like to kill a man, so he strangled the guy and buried him in a shallow grave under the platform.

Other than that he's been a very good friend and you have no fear he'd randomly kill you, though he might kill again.

Would you turn him in?

Yes.

It would suck, but how could you not?

I don't know, but my friendships are less based on how decent my friends are as human beings, and more on how decent they are as friends to me.

I don't know what i would do, but I can see myself doing nothing.