A 'cannibal prisoner' savagely attacked another lag in the toilet, biting off a chunk of his cheek and swallowing it.
Despite the grizzly assault, Dwayne Neil won't have his prison sentence extended.
The 34-year-old was already serving more than four years in jail for grievous bodily harm from 2015.
Neil, who will soon be due for release, sought out a prison rival at HMP Peterborough, Cambs, on September 20.
The pair had had disagreements before, and Neil found his victim and asked him for a fight.
They found an empty staff toilet and began to brawl.
In a cannibal-style move, Neil grabbed the man's face and bit off a chunk of skin.
In the scene out of a horror movie, the lag then swallowed his rival's flesh.
Neil refused to be interviewed about the grisly assault.
Cambridgeshire Constabulary charged him with assault occasioning actual bodily harm with intent.
After admitting to his blood thirsty crime at a previous hearing, he was sentenced at Peterborough Crown Court on November 4.
However Neil did not have his jail time extended, as his three-month imprisonment will be served concurrently with his previous sentence.
Det Con Robin Gray, who investigated, said: "This was a nasty and savage attack which must have been horrific for the victim.
"I hope this case highlights that we will do all we can to bring those who assault others so viciously to justice."
