The father of murdered schoolgirl Genette Tate, who disappeared in 1978, has backed new talks by police and prosecutors about the prime suspect in the case.
Devon and Cornwall Police have long suspected serial child killer Robert Black of murdering 13-year-old Genette, who was last seen in a rural lane in Aylesbeare, Devon. Her body has never been found.
There is now new hope of a prosecution in the case after Black last year lost an appeal against his latest conviction for the murder of nine-year-old Jennifer Cardy.
Genette Tate disappeared in 1978, prompting Britain's longest ever missing persons inquiry
He had argued that his trial was prejudiced because details about three other child murders he had already been jailed for were revealed to the jury.
Police told the BBC they are now liaising with the Complex Case Unit of the Crown Prosecution Service to see if the the appeal court ruling has "any bearing on the Genette Tate case".
It could pave the way for police to launch a case against Black based on his previous convictions.
John Tate told the BBC Radio 4 Today programme he feels "pretty happy" that the police are confident in their investigation, although he hoped they had not overlooked any other suspect by spending time focusing on Black.
Asked how he had coped in the decades since Genette went missing, he said it had been difficult as it was never far from his mind.
He said: "You look at everything that it could possibly be to do with her. You just cope very poorly sometimes."
Mr Tate said he believed the police had coped very well with the case, adding: "It's been pretty good... they wanted her DNA and it was taking forever and then we had a new Chief Constable, a female, and within two weeks she had it.
"She put it in a different way, she went privately with it and it worked out perfectly.
"I haven't been disenchanted with them apart from their lack of contact sometimes but what do you do?"
Devon and Cornwall Police said they were "liaising with the Complex Case Unit of the Crown Prosecution Service to ascertain if the 2013 Court of Appeal judgment following the murder of Jennifer Cardy in Northern Ireland (in which Black's conviction and the use of bad character evidence was upheld), has any bearing on the Genette Tate case".
The force added: "This liaison is still at a very early stage and will take some time to complete."
Black was found guilty in 1994 of the three child murders in the 1980s - those of 11-year-old Susan Maxwell, from the Scottish Borders, five-year-old Caroline Hogg, from Edinburgh, and Sarah Harper, 10, from Morley, near Leeds.
His reign of terror finally ended in 1990 when he was caught with a six-year-girl hooded, bound, gagged and stuffed in a sleeping bag in the back of his van in the Scottish village of Stow. He had sexually assaulted her moments earlier.
In 2011 he was prosecuted for a fourth murder - that of Jennifer, who was snatched as she cycled to a friend's house in Ballinderry, County Antrim, Northern Ireland, in 1981.
The paedophile is serving a total of 12 life sentences for murder and kidnap.