Mr Justice Blofeld, in his summing up, told the jury that no one saw Michelle Taylor and her sister Lisa outside Alison Shaughnessy's flat, or in the street at the relevant time on 3 June 1991. 'You will have to weigh the individual pieces of information and put them together like a jigsaw puzzle,' he said.
Michelle Taylor, 21, and her sister Lisa, 19, of Kemble Road, Forest Hill, south-east London, both deny murdering Mrs Shaughnessy, 21, of Vardens Road, Battersea, south-west London. She had been stabbed 54 times at about 6pm.
On the day of the murder the sisters said they spent the day in Bromley shopping and returned to the Churchill clinic in Lambeth by 5pm. They then watched television with Jeanette Tapp, a friend. Miss Tapp denies this.
Mr Blofeld described Miss Tapp as a 'very important' witness. He said that if her evidence was true then the sisters had lied.
The trial continues today.