A killer who escaped justice after murdering a schoolgirl hid evidence of his awful crimes in a lockup before going on to murder and rape more.
Elsie Frost, 14, when she was stabbed to death in a Wakefield underpass in October 1965.
When her body was inspected pathologists found stab wounds to her head, hand and back - and one of the killer's brutal incisions pierced her heart.
The teen's body was found by a man out walking with his children at the bottom of steps known locally as ABC steps, Yorkshire Live reports.
The tragedy sparked a huge police manhunt in which 12,000 people from across the county - most of them men and boys - were questioned.
A post mortem revealed the schoolgirl had died from shock and losing too much blood following the frenzied attack.
Elsie - who lived with her family in Lupset, Wakefield - was described at the time as a "model child" and she was expected to become head girl.
She was described as intelligent, bookish, and pretty.
The hunt for her killer made national headlines for weeks and, despite extensive inquiries, the murder weapon was never found and no one was ever convicted of her murder.
At the time of the murder, one arrest was made, but a judge cleared Ian Bernard Spencer, who was 33, of any involvement.
Decades passed but Elsie's surviving family members never gave up hope of finding out what happened to her and why.
Her sister, Anne Cleave, contacted the BBC on the eve of the 50th anniversary which led to Radio 4 journalists investigating the case and then West Yorkshire Police resumed its own hunt for the killer.
The police investigation, which reopened in 2015, involved a team of 14 who looked at thousands of documents and evidence.
In 2016, police officers arrested Peter Pickering, 78, on suspicion of murdering Elsie. Pickering - dubbed the Beast of Wombwell - stabbed and strangled Shirley Boldy in Wombwell, Barnsley, in 1972.
He was detained at a psychiatric hospital in Berkshire when police caught up with him in 2016.
It emerged that Pickering had been identified as a likely suspect within days of the murder but police were unable to trace him.
An inquest into Elsie's death in 2019 heard that a file on Pickering was sent to West Yorkshire Police from Scotland Yard. Officers ruled him out, wrongly believing they had already identified the killer.
The new inquest into Elsie's death was held after her brother and sister, Colin Frost and Anne Cleave successfully campaigned for a fresh review and comes after West Yorkshire Police revealed that Pickering was close to being charged with Elsie's murder at the time of his death in March 2018.
Mrs Cleave spoke of her anger that the case had been left "in limbo" following the exoneration of Ian Spencer in March 1966 - leaving Pickering free to go on to murder 14-year-old Shirley Boldy and kidnap and rape an 18-year-old woman in Barnsley in 1972.
She said: "Pickering's name had already cropped up because a file was sent up from Scotland Yard."
She continued: "The outcome of that, of course, is the fact that Pickering goes on to commit other crimes.
"If things had gone as they should have done in 1965, those events may not have happened and maybe then my sister's case would have come to full fruition."
Mrs Cleave told the inquest: "I've been very angry that nothing happened after Mr Spencer was released.
"That makes me very angry, nothing happened until Colin and I got things going again after dad died."
She added: "After March 1966, after Mr Spencer was released and exonerated, that's when things stopped."
The inquest heard that police in Wakefield were sent a file on Pickering from the Metropolitan Police on October 13 1965 - just four days after Elsie was stabbed to death as she walked back from a sailing club event.
On October 25, the force returned the file with a note, which read: "The file in respect of Peter Pickering was forwarded to this office making Pickering a likely suspect.
"Accordingly, extensive inquiries have been made but Pickering has not yet been traced."
In 2018, police revealed further details about their investigation that led them to prolific sex criminal and child killer Pickering, who was dubbed the 'Beast of Wombwell' for his sadistic crimes.
Pickering warned “watch what happens next” in a letter after his girlfriend dumped him – and days later 14-year-old Elsie Frost was dead, the Mirror reports.
The letter was never posted and, seven years later, Pickering went on to rape a teenager and murder Shirley.
The West Yorkshire Police probe into Pickering uncovered "damning" evidence that he had killed Elsie.
Police discovered Pickering had two secret lock-ups in Sheffield and Liverpool that were packed with suitcases containing handcuffs, women's underwear, diaries, letters, paintings and exercise books.
They found the unposted letter dated October 1965, which he had written to a girlfriend, who lived minutes away from the Elsie Frost murder scene.
After the girlfriend dumped him, Pickering wrote: "You have caused me to do what I’m about to do – you watch what happens next!”
“…I will surely go down in flames this time…I shall have to take someone with me when I go.
"So now what? To join the Devil…now I’m really going to get good and bloody nasty. Thanks to you."
Detectives also found out that Pickering had plotted with his mum to create a false alibi for the day Elsie was murdered.
Speaking about the investigation, Det Supt Nick Wallen said: "When we started we literally had nothing.
“No eyewitnesses, no DNA and no exhibits at all to work with, the evidence had all been destroyed. It seemed like mission impossible.”
The officer's team was days away from charging Pickering when he died of a heart attack in March 2018.
Detectives had contacted the secure hospital where Pickering was held in a bid to arrange an interview with him.
DS Wallen added: "He was a killer and his prey had been 14-year-old schoolgirls.
"He had committed sexual offences on at least two other girls of that age.
"A member of staff at the hospital told him West Yorkshire Police wanted to talk to him and the first thing he did was to call us.
"He said: ‘I know what you’re ringing about, you don’t need to worry about that. Please don’t waste your time. I remember that case at the time. I wasn’t in the country. I was in France.'"
DS Wallen said his senses started “tingling” as the convicted killer attempted to get his defence in first.
Police officers secured warrants for records and details of people connected to Pickering on the outside.
Yet he stuck to his alibi story when police questioned him.
“Peter Pickering’s problem is that he is a hoarder,” DS Wallen said.
“Everything he’d been writing and drawing over the last 40/50 years in custody he had kept it and then sent it to distant relatives, who stored it for him.
“He had two of these lock-ups paid for from his mum’s estate. They were floor to ceiling with boxes and suitcases. Officers had to read several hundred thousand bits of paper.”
Within the collection of documents, they found proof he was in West Yorkshire when Elsie died.
DS Wallen said: “He conspired with his mother to create an alibi. He wrote to her, saying ‘Get that doctor to say I’m in bed with the flu and get him to sign it if police ever come calling’.
“She then got the GP, who has since died, to make a false affidavit to the police.”
At the time of Elsie’s murder, Pickering had been on the run for a vicious sexual assault on a 14-year-old girl in the North East.
It is believed he returned to West Yorkshire, where he murdered Elsie.
As the evidence mounted police returned to Pickering for a final interview.
When challenged about not being in France, he said: “Actually, you’re right. I’ve got it wrong. I was in Barnsley, not in France.”
Speaking about the police errors in the 1960s, DS Wallen said: "We could see the fixation from police and how they were trying to make evidence fit.
“They were going back to certain witnesses and I can see words being put in mouths of certain people. It wouldn’t stand scrutiny today."
The inquest in 2019 concluded that Elsie had been unlawfully killed.
The hearing was told that Pickering's house had been put under surveillance by police in the days after Elsie's murder and that he was wanted for two serious sexual assaults on 16-year-old girls at the time.
He evaded police by dressing as a woman and escaping in a car, it was reported.
Pickering was arrested two months later but by that time Ian Spencer had already been charged with murder.
DS 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 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."
