The Incubus (1982)

Dr. Sam Cordell has just moved to the small town of Galen with his daughter, Jenny. But the doc seems to have chosen a bad time to move, as the community of Galen is suddenly plagued by a series of inhumanely brutal rape-homicides. Sam teams up with the local sheriff to try to stop the slaughter, a plight which may or may not be connected to his daughter Jenny’s new crush, a young man who seems to have chosen this seemingly inopportune time to completely lose his marbles.