Several weeks before Joe was released in the United States, a real-life mass murder with similarities to the movie's climactic scenes occurred in Detroit, Michigan. On May 7, 1970, a railroad worker named Arville Douglas Garland entered a university residence and killed his daughter, her boyfriend and two other students.[10]
During pre-trial deliberations, Judge Joseph A. Gillis saw Joe and strongly advised both the prosecution and defense teams to do the same. He then carefully screened each member of the jury pool and excluded any who had seen the movie. He also forbade any seated juror from watching the movie or discussing it with anyone who had seen it.[11] Although he brought with him multiple weapons and extra ammunition, Garland received a light sentence.[10]
Before and after sentencing, Garland received hundreds of letters from parents across the country who expressed sympathy with him. It was also reported that during the first weeks after his sentencing, he received no letters expressing outrage or condemnation of his actions.

After cynical drug addict Frank Russo persuades his reluctant 19-year-old girl friend, Melissa Compton, to try methadrine, she is hospitalized for an accidental overdose. When her father, Bill, a New York City advertising executive, arrives at Melissa's apartment to gather the girl's belongings, the addict taunts him. Infuriated by such callousness, Bill beats the youth to death. The dazed executive wanders into a workingman's bar and confides his crime to bigoted veteran Joe Curran. When Joe hears reports of the hippie's death on television he phones Bill his congratulations. The uneasy executive and exhilarated worker are soon socializing. Melissa, however, overhears her father describing the murder and runs away to Greenwich Village. While searching for her, Bill and Joe participate in an orgiastic pot party. Upon discovering that their wallets have been stolen, Joe forces the hosts to disclose the thieves' whereabouts. The enraged pair drive to a rural commune and slaughter its inhabitants. Too late, the executive discovers that he has shot his own daughter.