CCTV footage of a stabbing inside Canberra's jail — which injured a man so severely he needed plastic surgery — has been key evidence in the case against a convicted murderer, with the victim and witnesses refusing to work with authorities.
Kai Yuen, 34, pleaded guilty to recklessly inflicting grievous bodily harm in the ACT Supreme Court on Monday.
The victim was left with multiple stab wounds on his face, arms, abdomen and legs.
Yuen had already been serving time, a total of 28 years, for murdering his friend Brendan Welsh in 2010.
The footage, from last year, showed the pair throwing punches at each other in the Alexander Maconochie Centre, before the victim began to wipe blood from himself.
In the lead up, Yuen was seen with his hand in his pocket.
Prosecutors told the court they believed he was hiding a sharp object which he used in the attack.
The weapon was not found.
Some of the wounds were so serious that the victim needed hospital treatment and later plastic surgery.
The case had relied strongly on the footage, with the victim and all other inmates in the vicinity of the assault at the time refusing to talk to police.
Yuen will receive a final sentence next year.
