A PRISONER who butchered a fellow inmate with a pen and homemade scalpel had confessed he was going to kill months before the gruesome attack, an inquest has heard.

Cannibal fantasists Nathan Mann and Michael Parr were planning to eat Mitchell Harrison when they hacked him to death in HMP Frankland in Durham, County Durham coroner Andrew Tweddle was told.

Months before the pair lured child rapist Harrison to cell C22 in Frankland’s vulnerable prisoner wing, Mann had told his mental health nurse that he wanted to kill “a nonce”.

Mann, 25, also wrote graphic descriptions of how he wanted to kill a prisoner in a diary discovered by prison staff, and in a letter to the nurse he said he would commit the “goriest” killings ever seen to force a move to a segregated part of the prison.

The nurse, Susan Duffy, told Harrison’s inquest in Crook, County Durham, that she filled in a Security Information Report (Sir) after Mann said he wanted to kill in January 2011, 10 months before Harrison was attacked on Saturday, October 1.

Ms Duffy said Mann was manipulative and she believed he was making up claims of suffering from anxiety and hearing voices to get medication which he could sell.

However, Ms Duffy did treat Mann’s threats seriously and filled in the Sir, which was sent to the prison’s security department.

She said: “My gut instinct was that he would carry out those threats, he said he had nothing to lose.”

Robert Young, the acting deputy governor at HMP Frankland, said threats are an everyday occurrence in the prison, while prison officer James Winter said floor staff are only told a Sir has been made, not the specifics of the report.

He said officers would be told details if the security department deemed it to be important, which he admitted “rankled” with him.

Harrison, 23, was serving a four-and-a-half year term after being convicted of raping a 13-year-old girl in his home area of Cumbria.

Mann, who was serving life after he killed two vulnerable women in a Leicestershire nursing home, and Parr, who was sentenced to life at Newcastle Crown Court in 2003 for attempted murder after he tried to smother a patient at a hospital in which he was being treated, had been planning to kill an inmate for several weeks and had fantasised about eating their victim.

The night before the attack, the pair made a scalpel using a razor blade from a disposable razor and a plastic kitchen knife.

Detective Chief Inspector Steve Chapman said Harrison was chosen at random, and was lured to Mann’s cell on the pretext of keeping watch while the other two engaged in sexual activity in a period of free time for prisoners.

Once inside the cell, Mann jumped on Harrison and pushed him face down on the bed while Parr, who had closed the door, held their victim’s legs.

Mann then strangled Harrison, stabbed him in the eye with biro and severed an artery with the scalpel, which ultimately caused his death.

The pair then attempted to disembowel Harrison with a view to eating his liver, but the inquest heard that they “did not like the look of it”.

They then had a cup of tea before calling staff, telling officers that they had done something very bad and needed to be segregated.

Mr Winter described seeing a lake of blood in the cell, while Mr Tweddle called Harrison’s death gruesome and grotesque.

Both Parr and Mann were given life sentences in July last year after being convicted of murder and manslaughter on the grounds of diminished responsibility respectively.

The inquest is set to continue tomorrow (Tuesday, November 10).