Forced Entry

Forced Entry is a 1973 adult horror film written and directed by Shaun Costello under the pseudonym Helmuth Richler. It stars Harry Reems as an unnamed and psychotic Vietnam War veteran who sexually assaults and kills women who stop at the filling station where he works as an attendant. Called "one of the most disturbing and unpleasant porn features ever made," the film utilizes actual footage of the war, predominantly in the rape and murder sequences.

Synopsis from Wikipedia, CC BY-SA 4.0. Everything below written here.

Poster © the film's rights holders.