A student killed his guardian in a frenzied knife attack when he was under pressure from failing vital college exams, a court heard.

David Quartey stabbed consultant paediatrician Dr Victoria Anyetei 56 times as she sat in her car outside her home in Teynham Road, Dartford, on August 14 last year, it was alleged.

Maidstone Crown Court was told that Quartey, son of a High Court judge in Ghana, then had about two hours to get rid of vital evidence before "discovering" the 54-year-old mother's body.

Anthony Haycroft, prosecuting, said one piece of vital evidence was that Ghana-born Dr Anyetei's attacker bit her on the chin and the mark matched 22-year-old Quartey's teeth.

"The issue in this case is easily stated, but it is a complex case looking at all the evidence. It is whether David Quartey was the attacker as we allege.

"We say there is no motive as such. This is a case where a normal, placid, likeable young man snapped and lost control."

Nobody saw the murder and the evidence was circumstantial.

"However, circumstantial evidence can be very powerful," said the prosecutor. "We say this is such a case. We say the evidence is strong.

"Despite lengthy interviews, David Quartey was unable to explain this evidence. The Crown say he is linked to the murder by a number of separate and powerful pieces of evidence."

Quartey, of Humber Road, Dartford, denies murder.

The trial continues.