A footballer who killed his former girlfriend was given two life sentences today after becoming the first person in Britain to be convicted of a crime for which he had been previously found not guilty by a jury.

Mario Celaire, 31, was retried because of the abolition of the double jeopardy rule which had prevented anyone from being brought before a court twice for the same crime. The law was overturned in 2005 for cases where “new and compelling evidence” could be produced.

The new evidence against Celaire included a confession to Kara Hoyte, his new girlfriend, that he battered Cassandra McDermott, 19, to death in November 2001. When she came forward to give evidence, he pleaded guilty to manslaughter more than six years after he was initially cleared.

He was convicted in May of killing Ms McDermott and later attempting to murder Ms Hoyte in a separate attack. Today he was given concurrent life sentences at the Old Bailey with the tariff set at a minimum of 23 years.

Celaire’s conviction was made possible by the survival of Ms Hoyte, who was so badly beaten by the man, that she suffered permanent brain damage. Detective Chief Inspector Nick Scola, who led the investigation, said: “I would like to pay tribute to Kara Hoyte, whose bravery and determination to give evidence against Celaire, despite receiving near-fatal head injuries, was astonishing.”

There was loud applause and a shout of “rot in hell” at the Old Bailey as Celaire, a convicted rapist with a history of violence against women, was sentenced.

Judge Paul Worsley told Celaire: “You present a very real and continuing danger to young women with whom you enter into a close relationship.”

The judge said Celaire had waited until the very last minute to plead guilty to see if the evidence of severely disabled Ms Hoyte would stand up to scrutiny.

He told him: “Your delay in admitting these charges so long after the offences had been committed was callous and calculating.

“Both girls were vulnerable. They were alone, they trusted you, they let you into their homes where they thought they were safe and you showed them no mercy.”

Celaire, a former player for Brentford, was with the non-league club Maidstone United when he was arrested in 2007. He was known to the club’s fans as Mario McNish, having changed his name the year before.

He began going out with Ms McDermott when she was just 15, repeatedly beating her and once throwing her down the stairs.

She dumped Celaire after four years of abuse and met a new man but her ex-boyfriend began stalking her.

A driving instructor told police how he followed her on lessons and said: “He thought that if he couldn’t have her, no one else would.”

Miss McDermott was killed while house-sitting for her mother Jennifer, a senior probation officer, at her home in Norbury, south London, while she was on holiday in the West Indies.

Celaire of Sydenham, south east London, had either punched her or pushed her head into furniture, knocking her out. She choked to death on her own vomit.

He claimed in the first court case that Ms McDermott was alive and well when he left her and the jury acquitted him of murder and manslaughter after deliberating for less than three hours.

But in February 2007 he admitted the killing to Ms Hoyte, a part-time model, after she found papers relating to the court case at a flat in Walthamstow, east London. He then flew into a rage and struck her on the head with a hammer.

Doctors thought that Ms Hoyte would die from her brain injuries. But nine months after the attack, despite paralysis down one side of her body and extreme difficulties communicating, she was able to speak to detectives.

Prosecution lawyers applied to reopen the inquiry into Ms McDermott’s killing and successfully got the acquittal quashed in the Court of Appeal.

The ends of the case marked the conclusion of an eight year fight for justice by the family of Ms McDermott.

Sister Andrea McDermott, 30, said: “We knew Mario killed Cassie. Today we have been vindicated. We have had to wait eight years for it - eight years of hell.”

Mother Jennifer McDermott said: “This double jeopardy will give people the chance to say we can go back to fight again, we won’t give up."

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