Students Gabriel Ferez and Laurent Bonomo were tied up and stabbed
One of two men accused of murdering two students "sniggered" at photos of one of the dead men, a court has heard.
Laurent Bonomo and Gabriel Ferez, both 23, were murdered in a bedsit in New Cross, south-east London, in June 2008.
Dano Sonnex, 23, from Peckham, south London, "smirked" when police asked him how long it took Mr Bonomo to die, a detective told the Old Bailey.
Mr Sonnex and Nigel Farmer, 33, of no fixed address, deny murder, arson and false imprisonment.
The French students had been tied up and stabbed hundreds of times during the robbery.
The court heard they were tortured in an ordeal lasting nearly three hours before the room was set alight.
Mr Sonnex was arrested on 10 July last year at his grandparents' home in Peckham, south London.
He gave no comment to any questions when interviewed, the court heard.
However, Det Con Chris Mogan told the court he asked Mr Sonnex how long it took Mr Bonomo, who was stabbed 194 times, to die.
Det Con Mogan told the court he then said to Mr Sonnex: "You are smirking, almost breaking into a laugh."
Mr Sonnex was shown pictures of Mr Ferez, who had been stabbed 50 times, before and after he was killed.
Both men deny murder, arson, false imprisonment and perverting justice
"Again, you are sniggering," the policeman said to Mr Sonnex in the interview, which was recorded on audiotape.
Earlier a woman and a 16-year-old girl said Mr Farmer handed himself into a south London police station a week after the murders and said: "I just killed two people."
Lucy Downer, who was waiting at Lewisham police station with the girl, said Mr Farmer seemed "wired", as if on drugs.
Mr Farmer told them he had third degree burns and his hands were "bright red", said Miss Downer.
"I was unnerved by his behaviour," she said. "It was more than odd. I thought at the time that he was high on something."
She said Mr Farmer told them: "I just killed two people and the police don't want to do anything about it."
He then got up and said "I just killed two people in New Cross."
Mr Sonnex admits burglary, which Mr Farmer denies. The trial continues.