A police prosecutor described the attack as “disgusting and unprovoked”, and left the victim with serious facial injuries and no memory of the incident.

Thomas Johnson, 23, originally of Shepparton, pleaded guilty in the Bendigo Magistrates’ Court last week to assault charges stemming from the attack on January 28.

The court heard five men were eating lunch in the cell at 12.30pm when Johnson, who had been constantly fidgeting, stood up and approached one of the cellmates.

CCTV footage showed after about three minutes of conversation, Johnson punched the man to the head, causing him to jolt back in his chair.

The man covers his face, and Johnson grabs his head and knees him to the face more than six times.

The victim’s “whole body tenses up”, before another cellmate attempts to pull Johnson from him. Johnson punched the second man to the face, causing him to lose a tooth.

The first victim crawls on the floor and attempts to use the wall to stand up, before custody officers enter and detain Johnson.

The victim lost consciousness and suffered severe facial swelling.

He told police he was sitting in the cell when “next thing I was outside, I didn’t know what happened and I had a thumping headache”.

The court heard Johnson is completing a 22-month jail term, to be followed by a 24-month community corrections order for unrelated offences.

He also has a mild intellectual disability, which his defence counsel said “gave him the inability to deal with situations that are stressful”.

She asked for the sentence to be absorbed into his current jail term, but Magistrate Jennifer Tregent said that would be like giving him “a free hit”.

Prosecutor Senior Constable Cherree Blair agreed, and said it was a “disgusting and unprovoked attack”.

Ms Tregent said Johnson needed to have some sort of punishment for the assaults.

“It was a very brutal and sustained attack on a person who was confined and had no escape from you,” she said.

“There needs to be some form of accumulation.”

The man was sentenced to eight months jail, with six months to be served concurrently, meaning an extra two months was added to his overall term of imprisonment.