Author Jesse Hill Ford based the story on an actual event and people in his town. Many people in Humboldt were not happy after the novel was published and felt betrayed, especially after the film gave the story wider circulation.
Henry Fonda had to turn down the lead role, due to scheduling conflicts on Zwei dreckige Halunken (1970).
Lola Falana receives an "introducing" credit here, but she had three credited feature film roles in pictures released from 1966-67, including the lead in Lola Colt... sie spuckt dem Teufel ins Gesicht (1967).