He was receiving palliative care from cancer nurses at Ashworth, a high-security psychiatric hospital in the Liverpool area, when his death Monday was announced.
Brady was 28 in May 1966 when he and Hindley were convicted of murdering Lesley Ann and Edward.
Mosnter Brady, who imfamously tortured and murderer five children in Greater Manchester during the 1960s, died aged 79 on Monday.
Four of Brady and Hindley's victims were buried on Saddleworth Moor.
Fifty years on, 12-year-old Keith Bennett has still never been found - despite the belief that Brady knew the location and buried him on the Moors, where he buried three others.
In 2012 Brady's health advocate, Jackie Powell, was questioned by police after she told a television documentary Brady had given her a sealed envelope to pass to Mrs Johnson in the event of Brady's death.
Martin Bottomley, head of Greater Manchester Police's Cold Case Review Unit, said officers would act on "credible and actionable" information which would help them find the body of Keith. Hindley died in prison in 2002.
Ian Brady and Myra Hindley went down in history as two of the sickest serial killers ever to stalk the United Kingdom.
He left Glasgow at 16 and moved to live with his natural mother in Manchester after getting in trouble with the law, and assumed his stepfather's name.
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Moors murderer Ian Brady takes secret of victim's burial site to his graveThe evidence seen and heard at their Chester Assizes trial chilled the hearts of those who sat through it.
He said according to the BBC: "I would like an assurance before I do so that first of all the person who asked to take over responsibility for that funeral has a funeral director willing to deal with the funeral and that he has a crematorium willing and able to cremate Mr Stewart-Brady's body".
When it was rumoured Brady was dying last December, Mr Ainley said: "It is hard to know, without Ian Brady releasing a qualified medical report, the true prognosis bearing in mind previous stories concerning his poor state of health".
It has also been revealed, that one of the victims also had the humiliation of their murder being captured on tape by Hindley and Brady.
The couple repeated the method roughly every six months, picking up 12-year-old John Kilbride at a market in Ashton-under-Lyne, Keith Bennett, also 12, as he walked to his grandmother's home in Longsight, and finally Lesley Ann Downey. "As far as I am concerned, Ashworth Hospital can leave him out for the bin men".
"It's been years and years of anguish and pain for us and the families of the victims", Terry Kilbride, 62, told The Sun.
Pathologists said it was impossible to say whether Brady had sexually assaulted her.
Such is the notoriety of the Moors murderers that after 50 years the death of killer Brady wiped news of Britain's general election off most of the national tabloid newspapers.
A harrowing recording of her final moments, when she pleaded for her life, helped cement Brady's reputation after it was played in court.