A convicted killer who hurled boiling water at a female prison officer has had his jail term extended by appeal judges.
William Johnstone, 41, was put behind bars in 2002 after using both a hammer and axe to murder his mother's partner Sandra Black, before dismembering her body.
A judge ruled that Johnstone, from Gateshead, should serve 14 years before being eligible for parole, Chronicle Live reports.
Johnstone had been given another life term in 2006 after being convicted of an attack on a fellow inmate.
He was given a three-year jail term by a judge at Durham Crown Court this year after admitting attempting to cause grievous bodily harm at Durham Prison.
But three appeal judges on Tuesday increased that term to five years after concluding that it was unduly lenient at a Court of Appeal hearing in London.
They considered Johnstone's case after lawyers representing Solicitor General Alex Chalk argued that the three-year term handed down by Judge Ray Singh was unduly lenient.
The officer had suffered burns to her back after Johnstone threw water from a kettle at Durham Prison in April 2020, they were told.
Appeal judges heard that Johnstone, who has mental health problems, had been given a life sentence in 2002 after being convicted of murdering Sandra Black at a hearing in Newcastle Crown Court.
He was then given another life term in 2006 for an attack on another inmate, and told he should serve at least three years before being eligible for parole.
Appeal judges heard that he had served those minimum terms and become eligible for parole.
They were told that Johnstone had a history of violence, had 11 previous convictions for 22 offences and concluded that he continued to pose a risk.
Lord Justice Fulford, who headed the appeal judges' panel, said: "He clearly does pose a risk to prison officers and other inmates and members of the public when at large."
Mr Chalk said after the appeal court hearing: "Johnstone's act was a cowardly attack on a committed public servant acting in the execution of her duty.
"I want to make it clear that attacks on public servants, who protect society and deliver services on our behalf, should be met with appropriate prison sentences.
"I am glad that the Court of Appeal chose to increase his sentence today."
We previously reported how Johnstone, who was 23 at the time of the September 2001 murder, had said that "something snapped" before he launched his attack on Ms Black with an axe and a hammer, inflicting 95 separate injuries.
The product of a "grossly dysfunctional family", the judge said there was "some suggestion" that Johnston had been "repulsed" by "sexual advances" Ms Black had made towards him.
After the killing, Johnston went to "bizarre" and "macabre" lengths to dispose of the body. He hacked off both the victim's legs with a saw and wrapped them and Ms Black's trunk in pieces of carpet before trying to hid them in a coal shed in Bensham.
Johnston pleaded guilty to murder in November 2002 and was jailed for life.
But his was a crime which ultimately cost two lives, as his mother Teresa Johnstone was so overcome with grief at the loss of her lover at the hands of her own son that she took her own life.
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