Maniac (1980)

I warned you not to go out tonight

Frank Zito is a middle-aged, overweight loner living in New York City, where he works as the landlord of a small apartment complex. Unbeknown to his tenants, Frank is a schizoid serial killer who spends his nights stalking and killing women, scalping them and bringing the scalps and their clothing back home to decorate his steadily growing supply of mannequins.