Joel Fletcher, aged 23, and Anthony Rickett, 29, were sentenced for a combined total of 26-years for the brutal assault of another man in HMP Doncaster in January 2016, which left the victim with permanent scarring.
Sheffield Crown Court heard the pair slashed a 49-year-old inmate across the face after they entered his cell and locked the door. He is now scarred for life.
The court heard the attack was 'planned' and CCTV was covered up moments before the assault took place. The weapons used were never recovered.
Fletcher, was due to go on trial at Sheffield Crown Court in January 2018 charged with grievous bodily harm with intent.
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He pleaded guilty at the start of the trial and was jailed on Monday for 13-years and six months, with an additional three years on licence at the end of his sentence
Fletcher, right, formerly of HMP Doncaster, now of HMP Hull, was due to be released from prison next year after serving a sentence for burglary and robbery. This additional sentence will now run alongside his remaining jail term, and then continue.
Rickett, was found guilty of grievous bodily harm with intent following a trial.
Rickett, formerly of HMP Doncaster but now of HMP Lincoln, was sentenced to 12-years and six months in prison.
The 29-year-old was serving a sentence for robbery at the time of the assault, but was released last year to his address in Mexborough, Doncaster.
He was remanded back to prison upon being found guilty of the attack in January.
Temporary detective sergeant Alex Dorlin from the Prison Investigation Team said: “This was a nasty and vicious attack against a man in his cell, which has resulted in him being scarred for life.
“Fletcher and Rickett’s actions that morning were appalling and I am pleased they received lengthy custodial sentences for their violent crime.
“I hope this should serve as a warning to other inmates, that violence inside prisons will absolutely not be tolerated. We work very closely with staff and officers at the prisons, and we will always thoroughly investigate any reports of this nature, bringing offenders before the courts to be appropriately dealt with.”
Jerry Spencer, Serco Director at HMP Doncaster, said: “We take a zero tolerance approach to any and all violence in the prison and we are grateful for the excellent support our hard working staff are receiving from the police and the courts. We will always support any prosecution and we are very satisfied at the court’s decision.”