An investigation is underway after the death of a prisoner who was jailed for a samurai sword attack.
Raymond Allison died at HMP Holme House in Stockton-on-Tees, last month, the Ministry of Justice has confirmed.
The 47-year-old died in custody at the category C prison on Saturday, April 25.
The death has now been referred to the prisons watchdog the Prisons and Probation Ombudsman, which carries out independent investigations into deaths in custody.
No details of the cause of death at the prison have been released and no date has been set for when his inquest will be held.
According to GazetteLive, a Prison Service spokesman said: "Holme House prisoner Raymond Allison died in custody on April 25.
"The Prisons and Probation Ombudsman has been informed.”
The cause of death will be confirmed by the coroner at a future date.
The Ministry of Justice also confirmed that a second prisoner received hospital treatment on April 25 in a "separate incident".
The Prisons and Probation Ombudsman has also confirmed that an investigation is under way.
At the time of his death, Mr Allison was serving an eight year prison sentence, plus an extended two-year licence period.
He had been convicted by a jury of wounding a man with intent to do grievous bodily harm.
Mr Allison lunged and struck a man with a samurai sword, wounding his left thigh and gashing his left elbow which needed eight stitches.
The violence erupted at his home in Middlesbrough on November 2, 2016.
The victim believed there was a £5,000 bounty on his head at the time of the attack, after he was convicted for viciously beating a Staffordshire bull terrier named Bam for 30 minutes.
At the time of his sentencing, Mr Allison had 84 previous offences on his record, including arson, knife possession and numerous assaults including a GBH offence as a youth.
He was jailed for eight-and-a-half years in 2008 for aggravated burglary after he was in an armed gang of masked men which stormed a family home.
