Killer Amungst Us

An troubled man who seduces women and kills them later.

Pretty much taken from "Night of the Hunter" but still I do think that's a really good suspense idea.

So how about a really sick brother knows that he's doing this so he tries to warn his sister but he's done this before so it's kinda like a boy who cried wolf. Anyway, she meets this man after her brother drove away the last one and now he's actually killed her.

Motivation for being with someone.
Love.
They have something.
They are CLOSE TO SOMEONE!
OH SHIT!
THAT'S GENIUS!

Okay, so, long time ago the brother, before he was sick was really important. He must have something of value. Something like money but not like it because he lives with his sister. Uh. Maybe a really nice necklace or something.

NO NEVERMIND!
FUCK THE BROTHER PART!
So, the killer is a lot older than the brothers sister which is what first drives him to suspicion. It turns out that he knew their mother as a child and their was a really fancy necklace that she had that drove him...um...

So I don't really have anything besides, "a man that seduces women (completely) and kills them for his motives."
I guess I'll have to research some killers and see why they kill. Smarter move. I'll come back to this idea.
Ready. Break.