Meredith Kercher was killed by more than one person, according to a medical examiner.

Prosecution witness Vincenza Liviero told a court in Perugia on Saturday how the murder of the Coulsdon student was “carried out by more than two hands”.

Former flatmate and murder suspect Amanda Knox averted her eyes from graphic images of the 21-year-old student’s autopsy which were shown in court.

Miss Knox’s ex-boyfriend and fellow defendant Raffaele Sollecito glanced occasionally at the pictures, according to prosecutor Giullano Mignini.

Mr Liviero’s testimony was conducted behind closed doors after a request from the Kercher family to preserve their daughter’s memory.

He said the murder could only have been by one person if they had “three or four hands”. He also stated there had been sexual violence.

Mauro Marchionni, a gynaecologist and prosecution consultant, also testified how bruises on Kercher’s body suggested nonconsensual sex, Miss Kercher’s lawyer Francesco Maresca said.

A third suspect, Ivory Coast drifter Rudy Guede exercised his right under Italian law not to testify despite taking to the witness box as he had already been convicted and is serving a 30-year sentence for murder.

On Friday, coroner Luca Lalli, who performed the autopsy, told the court he was unable to confirm whether Miss Kercher had been raped.

But he said bruises and cuts on her face, neck, hands and legs suggested there had been violence during intercourse.

Mr Maresca said Mr Lalli initially also thought Miss Kercher had been attacked by more than one person but under cross examination admitted he could not rule out a solitary attacker.

Miss Kercher, a student at Leeds University, was on an exchange course in Italy when she was found stabbed to death in the house she shared with American Miss Knox on November 2, 2007.

Prosecutors allege she was killed during what began as a sex game, with Mr Sollecito holding her by the shoulders from behind while Miss Knox touched her with the point of a knife.

Prosecutors say Guede tried to sexually assault Miss Kercher and then Miss Knox fatally stabbed her in the throat.

Guede, who is appealing his conviction, did not meet the eyes of the other two defendants as he was escorted into court.

Mr Sollecito, 25, and Miss Knox, 21, both deny murder.

The trial continues.