When the police search for Keith Bennett's body on Saddleworth Moor in England was called off in 2009, the man in charge of the operation said he believed Ian Brady knew the exact location of the burial site.
The serial killer was said to have blamed changes in the landscape for being unable to trace the remains when he was taken back to the scene of his grisly crimes under police escort in 1987.
Following the Crown Prosecution Service's decision not to prosecute Ian Brady over Keith's murder, and that of Pauline Reade - whose remains were found earlier in 1987, Greater Manchester Police launched a covert investigation, Operation Maida, to take another look at the case.
A small team of detectives were gathered and, as a starting point, looked at the one obvious possible source of information - Brady.
He was approached via his solicitor in July 2003 but refused point blank to co-operate.
He waved officers away without uttering a single word when he saw them arrive on the ward at Ashworth High Security Hospital in Merseyside.
They pressed on without Brady's co-operation by analysing the original case file and re-examined the original statements of Brady and Myra Hindley, who died in prison in 2002.
They were convinced the clue to finding Keith's body - likely to still be preserved in the peat of Saddleworth Moor - lay in photographs that Brady took of Hindley at the crime scenes.
These were effectively souvenirs designed to act as signposts if they ever wished to retrace the path which led to their chilling deeds.
A remote area known as Shiny Brook, stretching up to five square miles, was identified from the photographs and was notable because it was up to a mile away from the burial sites of the other bodies.
Scientists indicated that modern geological techniques could provide a "feasible" chance of locating a foreign object in the moorland soil.
The search took place from 2005 to November 2008 without success.
During that period in late 2005 - despite Brady's earlier refusal to help police - the killer wrote to Keith's mother, Winnie Johnson and although he did not mention directly Keith by name or suggest where he was buried, Brady did refer to the "clarity" of his recollections.
He had ignored repeated requests from the late Mrs Johnson who wanted to find her son's makeshift grave and give him a proper Christian burial.
Police seized a number of documents in August 2012 following a search of Brady's living quarters at Ashworth after his "mental health advocate" Jackie Powell told a documentary he had given her a sealed envelope to pass to Mrs Johnson when he died.
The letter was never found and police said they could not rule out it was "yet more mind games" by Brady at a time when Mrs Johnson was close to dying.
Announcing in July 2009 that GMP had exhausted all avenues with the moorland search, Detective Superintendent Steve Heywood, then head of the force's serious crime division, dismissed theories that Brady would not know the location of Keith's body because of the passage of time, or fears that the moorland peat would have shifted over the decades and moved its location.
He told reporters: "If you look back at all the victims they were triangulated so that he could come back.
"Serial killers will generally try to use some sort of landmark - a way of coming back to a particular spot.
"They will revisit their activities on a daily basis. That is what they live for.
"People like Brady know what they are doing. They will have planned everything.
"He will have rehearsed daily what he did.
"It is my personal opinion that he knows where the body is."