This is an american film; probably late 80s-early 90s. I didnt see the entire thing, but i remember a guy randomly attacking women in their homes. The guy brings trash bags with him to dispose of their bodies afterwards. I remember detectives debating whether he’s insane, and another points out how he brings everything he needs with him, which makes him less likely to be insane.
Another part i recall is a detective finds the killer’s mother and asks about his childhood. The mother recalls her husband being very abusive towards her while her son watched. But the father never laid a hand on the son.