This movie is a semi-documentary based on the real-life string of mysterious killings that terrorized the people of Texarkana, Texas, in 1946. The murder spree became known as the "Texarkana Moonlight Murders" and ultimately would claim five lives and injure many others. The only description of the killer ever obtained was that of a "hooded man." To this day, no one has been convicted and these murders remain unsolved.
Some of the swamp scenes at the end of the film are actually recycled footage from The Legend of Boggy Creek (1972), Charles B. Pierce's first feature film.
During the film the narrator says "If you should ask people on the street what they believe happened to the Phantom Killer, most would say that he is still living here...and is walking free." The Texarkana police's best lead in the case was a car thief named Youell Swinney, whose wife Peggy supplied them with details about the murders only the police and the killer would know. As the admissible evidence against Swinney was only circumstantial, police instead charged him with felony theft of a car; under Texas law he qualified for the state habitual crime act and received a life sentence for being a repeat offender. He served 25 years before getting his case appealed and being released from prison at the age of 57. In 1975, he was arrested again for counterfeiting coins and stealing another car, was sentenced to two years in prison again, walked away from a prison labor job, was recaptured four days later, and sent to Leavenworth prison to serve an additional two years for escaping. Though still alive, he was incarcerated again at the time the movie was made and shown. He died in 1994 at the age of 77.
According to the interview with Andrew Prine on the Region 1 Shout! Factory release, Prine had to write an ending for the movie because the script didn't have one.
The sack the killer wears on his head was the inspiration for the mask Jason Voorhees wears in Friday 13th: Part 2.