Police say the unidentified man was allegedly seen fleeing the London apartment where Gabriel Ferez and Laurent Bonomo, both 23, who were tied to chairs, stabbed hundreds of times and set ablaze, the BBC reported.

The release of the suspect description comes after police released a 21-year-old suspect arrested Saturday in conjunction with the homicide investigation.

Detective Chief Inspector Mick Duthie told the BBC said the unidentified man seen fleeing the crime scene last Sunday was a potential suspect and any called on the public to provide any available information.

"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," Duthie said.

"A white man was seen running away from the block of flats after the blaze was started. He is a potential suspect."