The two students were stabbed repeatedly and set alight
A suspect arrested over the killing of two French students is being treated for burns to his hands and face.
Gabriel Ferez and Laurent Bonomo, both 23, were stabbed and burnt in an attack at a rented bedsit in New Cross, south-east London, on 29 June.
Their bodies were discovered in the property, which had been set alight after the murders.
The 33-year-old man handed himself to police and has been treated in hospital for his injuries.
A 21-year-old man arrested on Saturday was released without charge.
The badly burnt bodies of Mr Bonomo, from Velaux, near Marseille and Mr Ferez, from Prouzel, near Amiens, were found with more than 240 stab wounds.
Both men were biochemistry students and were in the third year of their masters degrees at Polytech Clermont-Ferrand in central France.
They were in London to take part in a research project at Imperial College and were due to return home soon.
Students and staff from the French institute took part in a silent march in Clermont-Ferrand on Monday as a mark of respect for the two men.
Claude Gilles Dussap, the Polytech director, said it was vital that students continued to work with each other.
"One of the messages of the silent march is certainly to say that European students will always collaborate with each other wherever that maybe, London, Helsinki, Copenhagen or whatever.
"It's the only way to make scientific and technical progress."
Mr Ferez's parents said in a statement to those behind the killings: "Rest assured that we will not leave you in peace."
They also said his killer would "not be able to live in hiding forever".
Post-mortem examinations gave the cause of death in both cases as multiple stab wounds to the head, neck and torso.
Tests also revealed Mr Bonomo suffered 80 wounds after he died.
The flat in Sterling Gardens, New Cross, which Mr Bonomo was renting, had been burgled on 23 June and a laptop was stolen.
Detectives believe their bank cards and two Sony PSP games consoles were taken on the day the pair were killed.
They have urged anyone who has been offered games consoles stolen from the flat to come forward.