Professor Rufus Crompton said at the Old Bailey that Alison Shaughnessy had fought to defend herself. 'While she was being killed, she probably defended herself and tried to avoid the blows. The wounds were inflicted in rapid succession. It could have been done in two or three minutes. She would have been unconscious in a matter of five to six seconds. She was not only bleeding to death, but was asphyxiated. Death may well have taken a minute or two after that, but not much longer.'
He said he counted 54 stab wounds on the body.
Asked by Mr Justice Blofeld whether the force used was beyond that of a woman, he replied: 'No. I thought it would suggest the capability of a female.'
The fatal wound was from a knife thrust behind her breastbone, which severed the carotid artery and her windpipe, Professor Crompton said. The wounds had probably been inflicted by a sharp, single edge knife with a five-inch blade - but he did not rule out more than one weapon being used.
The prosecution has alleged that Mrs Shaughnessy was killed by her husband's mistress, Michelle Taylor, and Ms Taylor's younger sister, Lisa.
Ms Taylor and John Shaughnessy had been having an affair and Mrs Shaughnessy was murdered in a jealous rage, according to John Nutting, for the prosecution. He said diaries kept by Michelle Taylor revealed her hatred for Mrs Shaughnessy and her 'dream solution' of removing her from the scene.
Michelle Taylor, 21, and her 18- year-old sister, Lisa, both of Kemble Road, Forest Hill, south London, deny murder.
They are accused of attacking Mrs Shaughnessy as she arrived home from work at her flat in Vardens Road, Battersea, south London, on 3 June last year.
Michael Unsworthwhite, a doctor, told the jury he saw two young women running from Mrs Shaughnessy's front door as he cycled home to Vardens Road on the day of the murder. 'Something about the two 'jarred',' he said. Although they appeared to be jogging, one was carrying a bulky bag as if they were going to the launderette. But they were running in the wrong direction. Dr Unsworthwhite added: 'They were not covered in blood or wielding axes or anything like that.'
The trial continues today.