A convicted child killer dubbed the "Beast of Wombwell" has died in a psychiatric hospital.
Peter Pickering, 80, stabbed and strangled 14-year-old Shirley Boldy in Wombwell, near Barnsley, in 1972 and was suspected of murdering Wakefield schoolgirl Elsie Frost in 1965.
On Tuesday he was convicted of raping a woman weeks before he killed Shirley and was waiting to be sentenced.
He had been detained under a hospital order since admitting killing Shirley.
West Yorkshire Police said Pickering died on Saturday night after falling ill in a secure psychiatric accommodation in Berkshire and his death was not being treated as suspicious.
Det Sup Nick Wallen said: "We can now formally confirm that Peter Pickering was the man we arrested and interviewed over the last two years as part of the renewed investigation into the murder of 14-year-old schoolgirl Elsie Frost in Wakefield in 1965.
"We strongly suspected that Peter Pickering was responsible for her murder. We had been liaising with the Crown Prosecution Service and it was our expectation that Pickering would be charged in due course.
"His unexpected death clearly means that will no longer happen."
In 1965 a major murder inquiry was launched after Elsie's body was found at the bottom of a flight of steps by a dog walker.
In 2015 police launched a fresh appeal to find her killer.
It came as a result of the BBC Radio 4 podcast series Who Killed Elsie Frost? which followed her brother Colin Frost and sister Anne Cleave as they sought justice for the schoolgirl.
Mr Frost said hearing about Pickering's death felt "like a hollow victory".
"We really needed to see this man in court," he said.
"That day's been taken away from us. We've been really close, but it's not going to have the right ending now.
"When the detective rang me this morning, I laughed it off. But as the day's gone on… I'm almost speechless."
Detectives said the rape Pickering was convicted of this week only came to light while they were investigating the murder of Elsie, who was stabbed in the back and head while walking through a railway tunnel, just off a canal towpath.
The woman he raped, who cannot be named for legal reasons, told his trial she did not think she would have been believed if she had reported the attack in the 1970s.
She was then persuaded by police to co-operate in 2016.
During the rape trial, Leeds Crown Court heard Pickering had lured his victim into his van before driving to a secluded spot in 1972.
He then subjected her to an ordeal that involved handcuffing her and burning her breasts with cigarettes.
The woman told the jury: "I remain of the fervent belief that whether he has a mental illness or not, the man is a monster and wherever he is now that's the right place for him to be."
Weeks after the rape, he abducted, raped, strangled and stabbed 14-year-old Shirley Boldy to death on her way home from school in Wombwell.
He later admitted manslaughter by diminished responsibility the same year and has been in secure psychiatric hospitals, including Broadmoor.
Most recently he had been detained at Thornford Park Hospital in Berkshire.