An attempt to block the release of a man convicted of beating and raping a pensioner has been rejected by the Parole Board.
Wendell Baker was given a life sentence in 2013 for attacking 66-year-old Hazel Backwell and locking her in a cupboard.
The Parole Board announced last month Baker was "suitable for release" following a hearing in April.
Justice Secretary Robert Buckland asked the board to reconsider Baker's release as it was "irrational".
Despite challenging the release, Mr Buckland's officials did not take part in a parole hearing to argue why he should remain locked up, the board said.
Baker, 63, became eligible for release on 15 March, after serving eight-and-a-half years of a life term for attacking Mrs Backwell at her east London home.
Mrs Backwell was beaten, raped and locked in a cupboard in 1997. She died five years later.
Baker was convicted in 2013 at a second trial, made possible by changes to "double jeopardy" laws, having been acquitted in 1999 when a judge wrongly excluded vital DNA evidence.
Her son, David, and daughter-in-law, Margaret, said they were "disgusted" at the refusal to stop Baker being let out.
"It's disgraceful, beyond belief," Mrs Backwell told BBC News.
The Backwells were never informed about Baker's hearing in April and had no chance to contribute to it, they said.
They learnt of the decision to release the prisoner last month from a newspaper reporter.
Retired High Court judge Sir John Saunders, who conducted the Parole Board's review, said: "Although (Baker) had committed a very serious offence which he continues to deny, the law is clear that such denial in itself does not mean that it was irrational to direct his release per se."
He added that Ministry of Justice (MoJ) officials had not objected to the views of prison experts who concluded Baker had met the release test.
"If the applicant (the Justice Secretary) disagrees with the evidence of the professionals and considers that the test is not met, then it would have been helpful if he was represented at the hearing or provided written representations setting out his concerns," he said.
Though released from prison, Baker will be on licence for the rest of his life, a MoJ spokesman added.