Detectives investigating the murder say the suspects in the shooting death of a 20-year-old man may be in Glasgow.
Tamba Momodo was shot several times in the car park at Bridges Business Park in Horsey, England, on October 13 last year.
He succumbed to his injuries.
Despite an extensive investigation and 24 arrests, no one was found guilty of murder.
A 10,000 reward is being renewed for finding those behind the murder a year after Tamba was shot.
Detective Chief Inspector Mark Belmy, a senior investigating officer, said: “Twelve months ago, Tamba Momodo was shot dead in the middle of the day in a quiet business park.
“Our investigation has made some good progress in the last 12 months, 24 people have been arrested, hours of CCTV have been watched and our interrogation has taken us to Glasgow and the Northolt area of London.
Despite this, no one has been convicted of his murder to date. I am fully committed to ensuring that Tamba’s family needs their answers and that there is justice for Tamba, which is why I am renewing my appeal for information.
“I know there are people out there who have information about Tamba’s murder, I know there are people who know who is responsible and I am directly appealing to them to go ahead. Come and share this information with crime stoppers.
“I want people with information to think about how they would feel if they had a son, a brother or a nephew. They want to be held accountable for what they do. Have information to talk about.
The detective added: “Crime Stopper is an independent charity, separate from the police, and 100 anonymous. Police never know the identity of a person who contacts Crime Stoppers.
“If the information they provide leads to the arrest and conviction of the Tamba killer, they could receive 10,000.”
Information provided directly to the police will not be eligible for a reward. Only information transmitted to Crime Stoppers via 0800 555 111 or an unrecognizable online form at www.crimestoppers-uk.org will be eligible.