The mother of Moors Murders victim Keith Bennett has died without knowing where her son is buried.
Winnie Johnson, 78, had been suffering from cancer for a number of years and passed away peacefully at a hospice earlier on Saturday, her lawyer said.
12-year-old Keith's killer, Ian Brady, has always refused to disclose the location of him victim's body on Saddleworth Moor above Manchester.
Keith was taken by Brady and his partner, Myra Hindley on June 16 1964, after he left home to visit his grandmother.
In a statement Ms Johnson's lawyer John Ainley said: "Winnie Johnson, mother of the last missing Moors Murders victim Keith Bennett, has died without discovering her son's whereabouts.
"Winnie aged 78 passed away peacefully at a hospice after she had been diagnosed with cancer some years ago.
"It is a terrible tragedy and I would ask the media to respect Winnie's family's wishes to be left to grieve in private at this distressing time.
"She will be sadly missed and was much loved by her family and friends."
Mr Ainley had represented her legal interests for the last few years and has reaffirmed her beliefs that Brady still holds the key to the missing child's burial spot.
He said: "Over the years and in all our personal meetings, Winnie has insisted Brady is the only person who could put her mind to rest and give her the chance to give Keith a decent burial before she passed away
"She was convinced Brady knew where her son was buried and she told me she wanted the search to continue to find Keith.
"Despite her personal appeals directly to Brady and via my office, Brady had persistently ignored the wishes of a grieving mother.
"She has died without knowing Keith's whereabouts and without the opportunity to finally put him at rest in a decent grave.
"It is a truly heartbreaking situation that this opportunity has now been irrevocably lost".