A coroner leading the inquest into Elsie Frost's death has described the lead suspect for her murder as "devious" and "dangerous".
The teenager was found stabbed to death by a railway underpass in Wakefield in October 1965.
A new inquest into the 14-year-old's murder has today (Tuesday) ruled that she was unlawfully killed, despite lead suspect Peter Pickering dying without being charged.
The hearing at Wakefield Coroner's Court was held this week after years of campaigning from Elsie's siblings Colin Frost and Anne Cleave, leading West Yorkshire Police to re-open the case in 2015.
The court heard on Monday how a file on Pickering was sent to West Yorkshire Police just days after Elsie's murder, but this was sent back to Scotland Yard as the force was unable to trace him.
Another man, Ian Spencer, was later charged with the murder and exonerated the following year, with the case left cold ever since.
Pickering meanwhile, who was dubbed the 'Beast of Wombwell' and described in court as a "homicidal maniac", went on to kidnap and rape a teenager, before murdering 14-year-old Shirley Boldy in Barnsley in 1972.
He died in custody in March last year, with West Yorkshire Police later revealing it was close to charging him at the time of his death.
The inquest heard Pickering's house had been placed under surveillance in the days following Elsie's murder, and was wanted for two serious sexual assaults on 16-year-old girls at the time.
But evil Pickering evaded detectives by dressing as a woman and escaping after a car chase. He was not questioned about Elsie again for 50 years.
Detective Chief Superintendent Nick Wallen, from West Yorkshire Police's Homicide and Major Enquiries Team who was re-investigating the case, told the inquest that officers at the time had seen Pickering's mother enter and leave his house, and eventually realised it was the suspect himself.
One of the officers gave chase, but to no avail. Pickering was not arrested until two months later, by which time Ian Spencer had been charged with the murder.
Mr Wallen told the court: "Peter Pickering, in my view, is a homicidal maniac... I'm absolutely convinced that he killed her."
He added: "We never thought we would have identified a suspect, that suspect was alive and we get that suspect to the doors of the Crown Court before he died.
"I'm desperately sad that Peter Pickering did not stand trial."
Coroner Kevin McLoughlin recorded a conclusion of unlawful killing.
He said: "Mr Pickering, it seems, was absorbed by Elsie Frost's murder.
"He has been exposed as a devious man.
"The picture that emerges is that Mr Pickering was a dangerous man, as far as young women were concerned."
He added that he was unable to apportion blame for Elsie's death, and that a prosecution would be "largely symbolic but of huge importance" to her family.
"Mr Pickering has spent over 40 years in custody. He served a life sentence literally.
"Mr Colin Frost said he had got away with murder but considering he spent the best part of his adult life in custody, it seems to me that Pickering did not get away with much.
"Apart from being declared as being the culprit."
Elsie's older sister Anne Cleave said following the inquest today that the family would never have "complete justice".
Speaking outside the Coroner's Court, she said: "You've got a jigsaw puzzle that is almost complete, except for one piece.
"So we do not and will never have complete justice for the murder of our sister."
Brother Colin Frost added that he was pleased the inquest had officially cleared Mr Spencer's name and identified Pickering as the likely killer.
Despite this, Mr Frost said Pickering had never faced justice for Elsie's murder, spending 40 years in custody for the murder of Shirley Boldy.
"He wasn't serving a sentence for Elsie's murder, that was the point", Mr Frost said.
"Not the fact that he'd been incarcerated for 40 years."