The secret of Keith's final resting place goes with Hindley to the grave

Winnie Johnson wrote a steady stream of letters to Myra Hindley over the years, pleading for help in finding her son's body, but she never got a single reply.

Keith Bennett was the third child to be killed by Hindley and Ian Brady, but his body has never been found and they were not charged with his death. The secret of where exactly on Saddleworth Moor the 12-year-old was buried has now gone with Hindley to the grave.

"I just hoped that maybe Myra might say something from her deathbed," said Mrs Johnson when she heard the news of Hindley's death.

"I have no sympathy for her even in death. The pair of them have made my heart very hard and really I just hope she goes to hell. She took 39 years away from me and I've suffered every day of that time."

Keith was meant to spend the night of 16 June 1964 at his gran's house, half a mile from home in Fallowfield, Greater Manchester. He wanted to ride there on his new bicycle, but Mrs Johnson was worried about the heavy traffic. So they walked together as far as the Stockport Road before Keith set out to walk the last couple of hundred yards alone. The short route took him down Westmoreland Street, where Ian Brady lived.

Keith never got to his gran's. Mrs Johnson did not know anything was wrong until the next day, when her mother said she had not seen the boy.

His murder was not part of the trial that sickened Manchester and the world. It was not until 1985 that Brady confessed, and Hindley then astonished detectives by agreeing to help them try to find the body.

The pair were taken back to the moor the following year and the corpse of Pauline Reade was found, but there was no trace of Keith.

Last year Hindley drew a map showing where they had parked, in a lay-by on the A635, but another search was in vain. It is thought the landscape may have shifted due to erosion. In one of 150 letters to a forensic scientist she claimed to have climbed to a flat area and kept watch while her lover pulled the terrified boy towards Shiny Brook. "I remember thinking then, as I later said to the police, that he looked like a little lamb being led to the slaughter."

Brady rejoined her after killing and burying the child, she wrote. Together they crossed Hoe Grain stream to reach a shale bank in which they hid a spade. Then they drove away.

"My boy is dead on those moors," said Mrs Johnson, who visits the spot twice a year, whatever the weather, to lay flowers at Christmas and on his birthday. "Brady broke his neck with a strap then buried him. She had nothing to do with it, according to her, but she was stood on top of the hill watching him."

The last time Mrs Johnson visited Shiny Brook was in June, when Keith would have been 50. Then, as always, she spoke out loud to his spirit. "I know he's here somewhere, listening to me. Each time I'm here, I reassure him that I'll never rest until I find him, and take him home."

She dreams of seeing his remains carried through the streets in a magnificent coffin by a team of plumed black horses. "I want him laid there, next to his step-dad Jim, so that the people of Manchester can pay him proper respects."

Keith would have been a wonderful son, she said. "Even as a lad he cared so much about others. He'd have made me proud."

Ian Brady wrote a letter last year offering to go back to the moor again to help find the boy, but that looks unlikely now he is ill and on hunger strike.

Mrs Johnson has vowed never to give up looking for Keith. "Hindley let me down, now there's only Brady," she said during an interview on Friday. Before leaving the media spotlight to deal with what had happened privately she attempted to appeal to whatever sense of mercy Brady had left, one more time: "Please, please tell me where my son is."