A highly-dangerous prisoner slashed the throat of another inmate after he suspected him of stealing his rosary beads from his cell.
David O'Brien, who was already serving a life sentence for slashing another prisoner's throat, attacked Dean Rawlinson with a toothbrush with a razor blade melted into it, on 13 October 2016.
The 39-year-old is serving time in HMP Manchester, also known as Strangeways, and will now be prohibited from contact with other inmates after the brutal slashing.
O'Brien had been moved from HMP Garth in Leyland, Lancashire, where he slashed another prisoner's throat, causing a 20cm gash to the victim's neck.
Rawlinson suffered a 12cm cut to his face, which required 16 staples, and the Manchester Evening News (MEN) reported that he was left traumatised by the incident.
"I will never feel safe in prison again. I have thoughts that my cell mate will stab me in my sleep", the 27-year-old said.
Convicted robber O'Brien was said to have been "paranoid" after losing his rosary beads before he invited Rawlinson into the shower so they could smoke.
O'Brien then lunged at Rawlinson with the knife but before the defendant could inflict more wounds, he was knocked off his feet by the victim.
Rawlinson fled noticing that O'Brien was also carrying a four-inch spike with cloth wrapped around it as a makeshift handle.
Rawlinson was taken to hospital and O'Brien admitted he carried out the assault saying, according to the MEN, saying: "Yes I cut his throat. He was stealing from me".
O'Brien had been sentenced to life, with a minimum of 86 months before parole can be considered.
He has now been handed another life sentence with a minimum of 21 years and four months to serve after he pleaded guilty to attempted murder, but had refused to leave his cell for sentencing.
O'Brien was originally imprisoned for a knife-point cash-in-transit robbery, where £15,000 was stolen.
The court was told the defendant has a personality disorder which leaves him unable to learn from previous mistakes and causes him to display aggression, reported the MEN.