In a statement issued by Scotland Yard yesterday, Mr Gabriel Ferez's parents Francoise and Olivier said: 'To those who committed this crime against our son and his friend, we say it is possible you did not anticipate how this might turn out.

'We plead with you to turn yourselves in to the police. You will not be able to live in hiding forever. 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.'

Their son and his friend Laurent Bonomo, both 23, were bound and stabbed to death at the latter's rented apartment on June 29.

Mr Bonomo had been stabbed nearly 200 times, while his friend received about 50 stab wounds.

Their badly-burnt bodies were found after neighbours in the New Cross neighbourhood called the police to report an explosion at the apartment.

Investigators believe the attacker or attackers had poured fuel over the bodies and ignited them in a bid to destroy evidence.

Yesterday, the police released a 21-year-old male suspect arrested early on Saturday in connection with the murders.

Detective Chief Inspector Mick Duthie, leading the investigation, said: 'I do not know why they were killed or who killed them but I believe the person or persons responsible would have been blood-stained as a result of this attack. A white man was seen running away from the block of flats after the blaze was started. He (could be) a potential suspect.'

Both victims were promising bio-engineering students taking part in a three-month DNA research project at Imperial College in London.

Police said the murders may be linked to the theft of two PlayStation game consoles on the night of the killings. A laptop computer was stolen from the apartment six days before the attack.

AGENCE FRANCE-PRESSE