Let's say we have a prankster, P, who is known for making prank calls. In these calls he enrages/bullies the call receiver; he is known for doing this in various ways (racism comes to mind).
He gets phone numbers to call in various ways, so he never knows upfront who he'll be calling.
He makes the calls anonymously, so the receiver has no way of knowing who's calling initially.
He received a call request with a number from a follower, F, to call some random person, R.
So, P calls R and makes him furious, to the point where R asks to meet up and deal with the thing they talked about. P accepts this offer over the phone, but has no intention to actually meet up with R.
R actually takes the offer to meet up seriously and shows up for the meeting. Not knowing P is not even coming, he meets 2 strangers. The 2 strangers have no idea why R is so angry with them; they end up being in the wrong place at the wrong time. Eventually R is so angry that in a blind rage he shoots both strangers, and both strangers end up dead.
Now what I'm interested in is who is responsible to what degree for this murder?
It seems pretty clear that R is guilty of the double murder.
But what are the roles of P and F in this whole case? Do they bear any responsibilities? Could they face jail time?
I'm most interested in any European country, but other places are welcome as well.
I'm also not certain to what degree European countries make a difference between homicide, murder and manslaughter. If I understand correctly, they are, respectively: killing in a somewhat legal way, unlawful killing with intention to kill, unlawful killing but without intention.