A violent teenage burglar who sank his teeth into a householder and threatened to kill him has been locked up indefinitely.

A judge warned Sunil Kumar he could spend up to ten years behind bars for robbing and burgling vulnerable victims.

Kumar, 20, of West Park Road, Girlington, Bradford, was sent to custody for the protection of the public. He was 18 when he embarked on a six-month crime spree, fuelled by alcohol and cocaine, Bradford Crown Court heard yesterday.

Between April and October last year, Kumar confronted two Bradford couples in their homes at night. He robbed two youths at knifepoint, threatening to kill one and holding the weapon to the other’s throat.

Prosecutor Dave MacKay said Kumar and another man were caught in the home of John and Norma Simpson, both in their 60s, in April 2007.

Mr Simpson returned home from work at 5am to find Kumar and his accomplice in the bathroom at the sheltered housing flat in Bradford. Mr Simpson alerted his wife, who had been asleep.

The intruders, wearing surgical gloves, barged past her in the hall, knocking her down and bruising her arm. They stole £30 from her handbag.

Kumar was arrested later but said he had been at a strip club when the couple were burgled.

In August last year he was sentenced to a community order with a curfew by Bradford magistrates for an incident with a pellet gun. And on October 9, Kumar robbed a 17-year-old youth of his phone at knifepoint at Bradford Interchange.

The next day, Kumar struck at the Bradford Housing Trust flat rented by Keith Fernie and his wife Tracey. Mr Fernie, 56, woke at 1am to find Kumar at the foot of the bed.

Kumar bit Mr Fernie’s arm, forcing him to let go, and jumped out of the window.

Kumar then reappeared with a knife. He thrust the weapon at Mr Fernie through the window, shouting: “I’m going to kill you”. Kumar tried to get back in the flat by the front door but was stopped by the security chain, Mr MacKay said.

The next day, Kumar held a knife to an 18-year-old youth’s throat near Bradford Interchange.

He robbed him of his mobile phone, two iPods, cash and his bus pass.

Kumar then went on to slap a 16-year-old boy across the face and steal phones from two 13-year-old boys before his arrest on October 31.

Asked by police about the burglary at Mr Fernie’s home, Kumar said he was at home or at work at the time.

Kumil’s barrister Gerald Hendron said he was young and had the ability to change.

Judge Benson said Kumar had a propensity to attack elderly and vulnerable people in their homes in the early hours.

He must spend a minimum of three years in custody, less the time he was locked up on remand.

Judge Benson said the Parole Board would not free him until he was no longer a serious risk to the public. The judge said it could be ten years before Kumar was released.

After the case, Mr Fernie said: “It is a relief he has been locked up for a long time. He is a very dangerous man and the best place for him is prison.”

Detective Constable Andrew Garland, of Bradford South CID, said: “We hope the sentence will be some comfort for Kumar’s victims and act as a deterrent to other would-be criminals.”