Adam was the nephew of Olympic sprinter John Regis

A spokeswoman for Scotland Yard said it was one of the lines of inquiry into the killing of Adam Regis.

The 15-year-old pupil was stabbed in Plaistow, east London, in March, as he returned home with friends from a night out at the cinema.

Police believe his killers may have used a small sword during the attack.

He was probably stabbed from behind as the blade penetrated his hand and entered his heart, police said.

CCTV footage released this week showed two young men getting into a nearby Volkswagen Scirocoo car minutes after the murder.

CCTV also captured a gang of five circling the Upton Park area in the car.

Officers have announced a reward of �20,000 for information leading to the conviction of the killers.