Detectives investigating the savage murder of two French students in London released details on Friday of items stolen from the flat where they were bound, stabbed and burned.

Police said a black Packard Bell laptop was taken in a burglary a week before the murders, while two Sony handheld games consoles were stolen last Sunday when Laurent Bonomo and Gabriel Ferez were murdered.

The 23-year-olds were bound, repeatedly stabbed and left in the blazing flat in New Cross, southeast London. Bonomo had been stabbed nearly 200 times, while his friend received nearly 50 knife wounds.

"We are keen to hear from anyone who has recently been offered a laptop and two personal game consoles, or knows someone who has unexpectedly come to have them," said Detective Chief Inspector Mick Duthie.

Police have received about 25 calls from the public after appealing for witnesses.

Professor David Canter, professor of psychology at the University of Liverpool, said detectives were left with a confusing and difficult crime scene.

"The ferocity of the killings is not typical of experienced criminals who want to get away as soon as they can," he wrote in the Times. "It points more to a confused mixture of habitual criminality and disinhibited anger."

The bio-engineering students were taking part in a three-month DNA project at Imperial College London.

Its rector Professor Sir Roy Anderson said the pair "had bright futures ahead of them", adding: "It is dreadful that their lives should end so soon."