An attacker who was told he could serve the rest of his life behind bars has been found hanging in his cell.
Martin Walker, 33, was found in his cell at the category A Woodhill Prison in Milton Keynes, Buckinghamshire, last night and pronounced dead at about 7.30pm, the Prison Service said.
He was serving an indeterminate sentence of imprisonment for public protection (IPP) after being convicted of causing grievous bodily harm and burglary, sources said.
A Prison Service spokesman said: "HMP Woodhill prisoner Martin Walker was found hanging in his cell at approximately 7pm on Tuesday December 27.
"Staff attempted resuscitation and an ambulance was called but he was pronounced dead at approximately 7.33pm. The police, coroner and next of kin have been informed.
"As with all deaths in custody, the independent Prisons and Probation Ombudsman will conduct an investigation."
Justice Secretary Kenneth Clarke has urged MPs to scrap the indeterminate sentences for serious criminals.
Presenting amendments to new laws on sentencing and punishment of offenders in November, Mr Clarke told the Commons that judges already had enough discretion to hand out life punishments to the most dangerous offenders.
And he said the indeterminate sentences had not worked properly since they were introduced under the Labour government in 2003, leaving thousands in prison beyond normal guidelines.
The IPP "experiment" left prisoners in a "Catch 22" situation, with no way of showing they were a "minimal risk to society", which they must do before they can be released, from behind bars, he said.
But Tory MP Philip Davies defended the sentences, which are aimed at those who pose a significant risk of causing serious harm to the public, telling Mr Clarke the reoffending rate for IPPs was just 5%.
Labour said Mr Clarke was taking a "weapon" out of judges' armoury and vowed to opposed the plan.