'The man handed himself in at a south London police station early this morning where he currently remains in custody.' On Sunday, police issued an e-fit of a man they said was seen running away from the scene.
They described him as 'white, between 30 and 40 years old, of slight or slim build and wearing a light-coloured baseball cap and a dark top, blue jeans and white trainers'.
On Sunday, the Ferez family pleaded for the killer or killers to come forward.
'You will not be able to live in hiding forever,' said Francoise and Olivier Ferez.
'You may be scared and feel like a coward, but you must recognise this terrible mistake you made. Rest assured that we will not leave you in peace.' The only other person held in connection with the case, a 21-year-old man arrested on Saturday was released the following day.
The bound and battered bodies of Ferez and Bonomo were found in a torched ground floor flat in the inner suburb of New Cross.
The pair were biochemists studying at London's prestigious Imperial College on an exchange programme from Clermont-Ferrand in central France.
Bonomo had been stabbed nearly 200 times while Ferez suffered around 50 wounds in a prolonged ordeal, unidentified police sources quoted by the domestic Press Association news agency said.
One theory is that the deaths were linked to a burglary at the flat, rented by Bonomo, on June 23 in which a laptop was taken.
Police believe two Sony PSP game consoles have since gone too and the victims' bank cards are missing. They are in touch with French banks to see if the cards had been used since the attack.
Detectives said officers were looking at forensic material from the first burglary, addding that there was no evidence that flat keys had been taken. The pair's mobile phones were also missing, they said.
The students had been due to return to Clermont-Ferrand later this month.
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