A teenage thug held another inmate captive at knifepoint at a young offenders’ institute and subjected him to a two-hour violent and degrading ordeal, a court heard.

Prison officers were unable to intervene as Kieran Betteridge beat and kicked his 16-year-old victim, made him strip completely and carry out various humiliating acts.

As well as forcing the boy to perform star jumps while naked, Betteridge at one point ordered him to urinate and then drink it on the ground.

When his ordeal finally ended, he was at first struck dumb, but then kept repeating to a staff member: “Please don’t let me die.”

Betteridge, 17, was sentenced to five years detention and training for what a judge called a “prolonged and sustained period of humiliation and abuse”.

Maidstone Crown Court was told he was in the exercise yard with others at HMP Cookham Wood in Rochester in April last year when he grabbed the victim around the neck and threatened him with an “improvised” plastic knife with tissue wrapped around the handle.

Staff raised the alarm but Betteridge, then aged 16, warned he would stab anybody who came near.

With the knife held at his throat, the victim was forced down onto his knees.

Prosecutor Keith Yardy said it was decided it was safest for officers to retreat from the yard, leaving Betteridge alone with the terrified teenager.

Staff were frustrated in their attempts to negotiate with him.

He continued to make threats to the victim and punched him. He then ordered him to strip to his boxer shorts and do star jumps.

“The victim was clearly in considerable fear,” said Mr Yardy.

“He stamped on his groin hard. The boy rolled around on the ground in pain.”

He was told to put his boxers back on and then do cartwheels. He was grabbed by the hair and kicked in the head while on the ground.

The victim was further made to lick the ground and dance. He was told to take his boxers off and squat and jump up and down with his hands in the air.

Betteridge made him stand in front of the house block where other inmates could see. Some encouraged him while others told him to stop.

“He made him lick the soles of his trainers,” said Mr Yardy.

“He made him crawl around on his hands and knees and lick the floor.

“He kicked him in the back and dragged him across the ground. He tried to get him to defecate and told him he was going to eat it. He couldn’t.

“He told him to urinate, which he did. He made him drink his own urine while on the floor and crawl around in it.

“The victim was clearly in pain and distress and shock. Officers eventually entered the yard and were able to knock them both off the bench and separate them.

"He kicked him in the back and dragged him across the ground...he tried to get him to defecate and told him he was going to eat it" - prosecutor Keith Yardy

“The victim was removed. He couldn’t speak initially he was so shocked and traumatised.

“He had difficulty in walking. He was escorted to an ambulance.

“He kept repeating to an officer, which caused her distress: ‘Am I going to die? Please don’t let me die’.”

The victim suffered a bloody nose, scratches to his face, grazes to both arms and his left eye was swollen.

When restrained, Betteridge, who was serving a sentence for robbery, kicked out at a prison officer, leaving him concussed.

He admitted false imprisonment, assault causing actual bodily harm, possessing a knife and common assault.

Mr Yardy said the victim declined to speak to police because he would be considered a grass by both other inmates and his family, who would beat him when he was released.

Iestyn Morgan, defending, said Betteridge, who was taken into care at the age of 13, suffered from ADHD.

He said of the incident: “It very quickly got out of control. He does feel remorse.

“He doesn’t begin to justify his behaviour and felt sorry for the victim having degraded him in this way.

Judge Heather Baucher said: “It is in a prison context, which is a hugely aggravating factor.”

She told Betteridge: “I have seen a suggestion this started out with others going to be involved and it was some sort of joke.

“But if it did start as a joke I don’t believe for one moment he thought he was subjected to a joke from the minute it started.

“Why? Because he had a large knife held to his throat.

“He was held captive for two hours, during the course of which he was subjected to the most degrading humiliation.

“It must have been absolutely horrific for some of the witnesses. No doubt, some egged it on. You felt encouraged by that.

“You had every opportunity to pull back and didn’t do so. He was so shocked afterwards, he became mute.”

The judge said she had pulled away from imposing an extended sentence for public protection, as it was not necessary at his age.

Mr Morgan applied for an order that Betteridge should not be identified because he was under 18.

But describing it as “a rare and exceptional case”, Judge Baucher said: “While I am fully aware of the welfare of the child, I am lifting reporting restrictions in the public interest.”