A teenager being sought over the murder of a young father in east London may have fled abroad, police have said.
Police have carried out searches for Bradley Tucker
Scotland Yard has alerted Interpol, ports and airports of its search for Bradley Tucker, 18.
Detectives want to speak to Mr Tucker, who is from Canning Town, east London, about Peter Woodhams' death last month.
Mr Woodhams, 22, was killed after an earlier confrontation with youths in Canning Town. He had been stabbed in similar circumstances in January.
Det Supt Vic Rae said finding the teenager, who has not been seen since the day of Mr Woodhams' death, was a "principal line of inquiry".
He said that they had been unable to find Mr Tucker, who had been living in nearby Butchers Road, despite a number of searches in the Custom House area.
"We believe he may have been involved in the altercation with Peter Woodhams before the shooting," he said.
Det Supt Rae said that the possibility Mr Tucker may have left the UK was a "definite line of inquiry".
"There is no record of him having travelled but that does not mean he has not travelled outside the country," he said.
People are advised not to approach Mr Tucker.
He will also face questions about an attack on Mr Woodhams in January when he was stabbed.
Mr Woodhams was a satellite television engineer who lived with his fiancee and their three-year-old son.
He was stabbed on 21 January, apparently after confronting a gang for throwing a stone at his car. His fiancee has said a group of youths continued to intimidate them following that attack.
At about 1900 BST on 21 August, Mr Woodhams was shot near his home after a confrontation with a group of youths outside a parade of shops.
He staggered home and collapsed in front of his fiancee, dying shortly afterwards.