Michael Parr and Nathan Mann, two prisoners at Frankland Prison in Durham, England, were sentenced by a judge to life in prison for killing and disemboweling a fellow inmate last year, the UK's Press Association reports.

According to the BBC, Parr, 32, and Mann, 23, cut the neck of Mitchell Harrison, a 23-year-old convicted of raping a minor. The pair, however didn't stop there; they then proceeded to cut open Harrison's stomach with the intention of eating his liver.

The Press Association, via The Guardian, offers more of the sinister details:

Mann, described by a psychiatrist as "a remorseless, callous psychopath" who "harbours cannibalistic urges", also stabbed Harrison in the eye with a pen and, after he was dead, cut his stomach open. He and Parr had planned to cut Harrison's liver in half and share it, but could not bring themselves to do it, the court heard.

According to the BBC, the pair fantasized about beheading and disemboweling fellow prisoners.

"Because of the risk these prisoners pose I cannot envisage the circumstances where either of them are ever released," Justice Peter Openshaw said, according to the Durham Times.

"They will face the fact that they may well end their lives in prison," he added, according to The Times.

Mann was sentenced to life in prison in 2008 for killing two women in a nursing home, according to Metro, while the Daily Mail reports that Parr was serving a life sentence for the attempted murder of a patient in a psychiatric hospital.

According to the Durham Times, Harrison was serving four-and-a-half years for raping a 13-year-old girl.

"Mitchell Harrison was a young man who was by all accounts a model prisoner at HMP Frankland," said Steve Chapman of the Durham Police said in a statement, according to ITV News. "Although his family never condoned his past actions, he was still their much loved son and brother and they were supporting him as he served his custodial sentence. His untimely death, and the horrific nature of it, left his family devastated."

According to the Ministry of Justice, Frankland Prison has a capacity of 859 inmates.