According to your opinion, what obsession does someone has that might kill somebody?

Um, this is rather morbid. I've only taken up to second year psychology at university but I'm pretty sure that obsession has to overriding psychosis with violent elements to actually hurt somebody.Obsessions alone like in OCD are fairly benign when it comes to their physical effect on other people.

i dont now much about this but i think if someone was obsed with blood maybe they would kill people or if someone was obsed with drugs they would ofer somebody dangorus drugs that could kill them maybe buut that is my opinion