A law student who stabbed his guardian 56 times because she had pressured him to resit his failed exams was jailed for life yesterday.

David Quartey, 22, was convicted of murdering Victoria Anyetei, 54, in a “frenzied attack of enormous brutality” as she waited in her car to take him to college for extra tuition.

The student, the son of a High Court judge in his native Ghana, had spent the weeks before the killing lying to Dr Anyetei about failing three of his six law exams.

It was on the morning of August 14 last year, after Dr Anyetei had found out his results and was preparing to inform Quartey's parents, that the student turned on the doctor he called “mum”.

Maidstone Crown Court was told that the “normal, placid, likeable young man snapped” and in “an episode of uncontrollable rage” repeatedly stabbed his guardian as she sat in her Toyota Avensis in the drive of her home in Dartford, Kent.

Judge Jeremy Carey said: “All she wished was to help him make the best of his life. He should have been deeply grateful to her. Instead he came out of that house with a knife, where he stabbed the defenceless Dr Victoria Anyetei.”

He added that one of the most sinister parts of the crime was that Quartey had tried “in a cold and calculated way to cover his tracks”.

Quartey, whose family in Ghana became friendly with Dr Anyetei after she saved the life of one of their children, had been staying with the doctor's family since October 2005.

He had come to the country with the intention of studying for a £14,000-a-year law degree after he had completed the foundation course at Kensington College of Business. But his poor attendance and failure to pass his exams twice were putting his visa in jeopardy, the court was told.

After Dr Anyetei found out that he had failed again she told him he had to do resits. Her son, Andrew Thompson, told the court that Quartey had confided in him that he did not want to because he had no hope of passing a third time.

Mr Thompson, 21, who was also studying law and living in the house, told the court that on the morning of August 14 he had been asleep when his mother, a paediatrician at St Thomas' Hospital, London, came into his bedroom. He said that he remembered his mother shaking him and saying: “David's scaring me, he's acting strange.” Mr Thompson said he was half-asleep and did not pay attention.

Two hours later Quartey came into his room and asked if he wanted to share a cigarette outside. Anthony Haycroft, for the prosecution, said that this was an attempt to lure Mr Thompson outside so that he would see the body first. Moments later Mr Thompson heard shrieks from Quartey and rushed out to find his mother dead in the car, with Quartey shaking her.

During the police investigation Quartey was interviewed by officers a number of times as a witness but he did not become a suspect until a month after Dr Anyetei's death.

The murder weapon, believed to be a single-edged knife no more than six inches long, was never found.

Ordering Quartey to serve a minimum of 15 years in jail, Judge Carey said: “I assess David Quartey to be a highly dangerous young man, someone who poses a significant danger even to close friends and family.”

Dr Anyetei's brother, Jonathan, said yesterday that his sister's death had “left a vacuum in our lives which will never be filled”. He added: “She was one of the leading members of our family. She helped the weaker ones in the family and was always there whenever anyone had a problem. Victoria was a very kind, humble, intelligent and very loving sister, mother, friend and doctor.”

Detective Superintendent Anne Brittain, of Kent Police, said: “This was a challenging case as there was initially no clear motive or suspect. Dr Anyetei led a professional and relatively simple life which revolved around her family, church and work.

“Quartey lied and continued to lie about circumstances leading up to her death and tried to cover up his crime.”

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