We have different definitions of friend, methinks. When I call someone a friend (I refer to most of my acquaintances as buddy or some other such term), I mean that i love them as if we were family. I can no more replace a dear friend than I could my baby sister.
Put another way: friendships are valuable. I’d sacrifice one if I suspected a friend was a serial killer; I’d sacrifice one if I KNEW a friend had committed an unjustified murder. But over a hunch, with no real evidence? No, nein, nyet, non.
I am not simply standing by idly. I have decided (given the information in the OP) that my friend likely killed the victim and that he was justified in doing so. I have also decided that my friend poses no risk to anyone else and that turning him in would not help anyone.
I am not pretending that I would not do the same thing you are doing, I just don’t know. But in reality he was not justified in killing the man, we don’t know the circumstances of the molestation only his version. You really don’t even know for certain his motivation in killing this man, again you only know his version. I have spent many years around vitims of child abuse, as well as abusers and families of the same. I know the truth is very seldom accurately relayed in these situations before the victims or perpetrators have gone through considerable recovery. Your friend needs to be held accontable for what he did, and yes he is a danger to others and himself at this point.
Would not turn him in, would not question him, would not even let him know I know the sob is dead. Like Sgt Shultz, ‘I know nothing’.
I don’t know that he did it and I’m not about to ruin a friendship over suspicion, nor am I going to let someone know I think they might be guilty. If they are innocent I’m hurting their feelings, if they’re guilty I’d rather they didn’t think they have to get rid of me too.
Even if for some reason I was questioned I don’t know anything, so there is nothing to tell.
However I will not perjure myself for anybody and once a ‘friend’ asked me to lie to the police for him and lie to the court for him. Nope! It was over a DWI though, not a murder.
FWIW I was kind of in this situation and I had my suspicions and I kept my mouth shut. Other people didn’t but the death was ruled accidental anyway.