I would kill in vengeance for one of my immediate familiy members, if I knew who the killer was. Fuck calling the cops in that case. I would go buck nutty if it was my brother, dad or mom. But if it's a random act of violence and I don't know who the killer is personally, the killer gets away, but I'm able to indentify him, then yeah, why the fuck not give the cops some info. That's not snitching in that case, that's just trying to solve a crime that happened to an innocent person.