A fire chief was wrongly convicted of rape after police failed to investigate a blackmail claim against the man who accused him.
A High Court judge is now asking why, the Telegraph reported.
David Bryant, 67, was sentenced to eight and a half years in prison after Danny Day wrote a letter and went to police accusing Bryant of sexually assaulting him when he was a boy.
Bryant spent three years in prison before his conviction was overturned in the Court of Appeal in 2016, after it emerged Day had previously sought medical help for being a compulsive liar.
In 2012, Day posted a letter to Bryant threatening to make him pay and demanding he speak to him.
Speaking on ITV's This Morning in 2016, the Bryants explained how Day had threatened them with the letter, which read:
"Dave, its Danny Day. 35 yrs ago I used to collect the glasses in the Legion and I am the same one that you ... played darts with in the fire station (remember!).
"At 6 o'clock tonight, I am going to the police station to report what went on and at 7 to the national papers. I think it is time you and me had a chat. One way or another you will pay for what you done."
Bryant's wife Lynn, who died shortly after he was released from prison, contacted the police after they received the letter, but the force did not get back to them in time.
Day then went to Dorset Police in 2012 accusing Bryant of sexually assaulting him in a fire station in Christchurch in 1977.
In a High Court judgment, Master Gary Thornett, has now said officers pursued the rape case against Bryant rather than investigating Day for blackmail.
"This [letter] would not strike any reasonable person as anything other than a blackmail note," he said in a written judgement.
"It is clearly threatening. The invitation to make contact seems well away from a need to discuss and elicit an apology but instead seek either a financial payment or retribution through the threat of police involvement and publicity."