It would be a terrible and sad day when that happened. However, if we're talking about death and the potential of other lives being taken or other horrible crimes,It would be a terrible and sad day when that happened. However, if we're talking about death and the potential of other lives being taken or other horrible crimes, then there would be a moral imperative, then there would be a moral imperative. Certainly in the UK, there would be the added pressure that when the authorities caught up with the perpetrator, if you had not immediately handed them in when you could have, you too could've been prosecuted for obstructing the course of justice.

Honestly, I would have to consider this reprehensible thing and many other circumstance like how it affects the world and likeliness of it ever happening again. This question is written to vaguely for a definitive answer from me.

Yes, it would destroy me but I couldn't live with that if I didn't

Yes I would.

I'm afraid I would have to or I wouldn't be able to live with myself

Yes.

No, but I would blackmail them.

Nope. Nor would I turn in a brother, sister, mother, father, or wife/gf.

Hide the knives.
Sometimes children are not susceptible to parenting.

It depends on the context.

Child? No.
18 years old or older? Yes.

If you mean illegal, then yes.

Yes

Yes

Yes

I don’t know. I’m torn