By Nadia Gilani

THREE years after a teenager was brutally shot dead in front of hundreds of potential witnesses, cops are offering a £20,000 reward to find his killer.

James Andre Smartt-Ford, 17, was killed at a disco event at Streatham Ice Arena attended by more than 300 people on February 3, 2007.

The victim, known to his family as Dre, was at the bottom of some stairs leading on to the rink in Streatham High Road when he was approached by a black youth wearing dark clothing just before 11pm.

Two shots were fired and he staggered several metres on to the ice before collapsing.

Detectives from the Mets Operation Trident are investigating, but no one has been charged in connection with his murder.

Police are now concentrating their efforts on the Angell Town Estate in Brixton and were handing out leaflets appealing for information there on Wednesday.

A Met spokeswoman said people who either live or frequent that estate are believed to have crucial information.

Gary Trowsdale, managing director of the Damilola Taylor Trust, has joined calls for people to come forward with information.

The trust was set up in memory of the 10-year-old who died after he was stabbed in on the North Peckham Estate in 2000.

It took six years and three trials before his killers were brought to justice.

Mr Trowsdale said: One of the biggest problems we face is the wall of silence.

The fact is that these killers just melt back into their communities, and that families dont find closure as a result.

I would would urge people of South London who know anything to take responsibility and come forward otherwise this family will continue to suffer until they get closure.

Detective Chief Inspector, Gordon Allison, from Trident said: We want to hear from anyone who may remember something from that night.

These witnesses have the power to bring an end to this and to take dangerous people off the street who cause harm to the community.

Four men have been arrested and bailed to return to South London police stations pending further inquiries.

Anyone with information is asked to call the incident room on 020 8247 4554 or Crimestoppers, anonymously, on 0800 555 111