The murderer of Northampton teenager may have 'offloaded' information onto a confidant over the past 40 years, the lead detective in the case believes.
Sean McGann left his grandparents' home in Victoria Gardens on Tuesday, April 17, 1979, with a pound in his pocket to visit the funfair on Midsummer Meadow.
But he failed to return home that evening and the teenager's body was found by a passerby at 8.10am the following day in a service road that runs behind a group of houses in Birchfield Road East.
He had been strangled and to this date, no one has been brought to justice over the murder. Though police initially believed it to be a sexually motivated attack, Sean had no other injuries.
But with today marking the 40th anniversary of Sean's death, police have released further details of fresh evidence in the case.
A recently discovered letter, sent to the McGann family in 1991 from an unknown source, purports to have information that could lead to the killer.
Speaking yesterday, lead detective DCI Ally White launched a fresh appeal for the author of that 1991 letter to come forward.
But he also believed that, over the course of the years, someone must have been confided in by the killer.
"This is an appeal for information," he said.
"I don't expect the offender to come forward and tell me that they were the murderer, but if that person has offloaded onto you and it is in your conscience and you have been waiting for a reason to offload that information yourself - then now is the time, 40 years on from the death of Sean.
"I want to appeal to the author of that letter to come forward and let us know what you know."
DCI White said the force's original investigation was not without criticism.
Original lines of enquiry appealed heavily to members of the gay community to come forward with information, as a public toilet block at Becket's Park was a known meeting or so-called 'cruising' place at the time.
Chronicle & Echo headlines written during the 1979 investigation suggested that police were searching almost exclusively for a killer among that community as well.
DCI White said officers from 40 years ago - and the headlines running in the Chron - became 'miopic', or short-sighted.
"It was a different time and there were different attitudes," he said of the 1979 investigation.
"The truth is this could have been anyone.
"Fortunately, as a police service, we are more enlightened. We are working together with all parts of the community now rather than against."
It is not known whether Sean ever made it to the fair, or what happened to the orange Campari jacket he was wearing at the time.
Though DNA was discovered on the recently obtained letter from 1991, the source of it has not also been possible to attain.