Killer with Mannequin Head and Black Robe

by K.W.
(USA)

I remember walking in on my brother and dad watching a horror movie with a killer who wears a mannequin head and black robe-like thing and as a girl is preparing to take a bath, he runs in and holds her head under the water until she drowns, then leaves her floating there.

There's another scene with people's heads in plastic bags and they have shocked expressions and don't look realistic. In another scene, a girl is in the woods at night (a very common occurrence, I know).

What is this film?