A second man arrested by police hunting the killer of two French students was taken to hospital today.
Police declined to reveal the nature of injuries suffered by the 33-year-old man, who handed himself in at a south London police station.
Officers may now have to wait some time until they are able to question the suspect over the deaths of Gabriel Ferez and Laurent Bonomo.
The badly burned bodies of the two 23-year-olds were found after an explosion at a rented bedsit in south east London eight days ago.
Investigators found they had been bound, gagged and tortured before petrol or a similar inflammable liquid was poured on and around their bodies.
Police said forensic searches at the severely-damaged ground-floor property in Sterling Gardens, New Cross, could continue for several weeks.
Detectives are following up dozens of new leads after an anniversary appeal for information at the scene last night.
More than 100 people who attended services at the nearby Baptist Church in Cottesbrooke Street have been approached by police.
Officers stopped cars in streets around Sterling Gardens last night to hand out leaflets and an e-fit of a suspect seen fleeing the scene.
The man is white, aged 30 to 40 and slim. He was wearing a light-coloured baseball cap, dark top, blue jeans and white trainers.
Detectives said they still do not know if one or more people were involved in the attack some time between 1am and 10pm on Sunday June 29.
Detectives have also questioned a 21-year-old man, arrested on Saturday, over the murders. He was later released without charge.
Mr Ferez's parents have appealed for the killer to come forward.
"We plead with you to turn yourselves in to the police. 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. We will not leave you in peace."
Mr Bonomo was stabbed nearly 200 times, up to 80 of the wounds inflicted after he was dead, while Ferez suffered nearly 50 knife wounds.
Six days earlier, Mr Bonomo disturbed an intruder stealing a laptop computer.
Experts have found no evidence of forced entry after the murders, suggesting that keys might also have been stolen.
Two Sony handheld games consoles were also taken. Credit cards are also believed to be missing.