Taxi drivers who saw a colleague shot at their Bradford base today questioned police efforts to trace his killer.

Six months after Mohammed Basharat was murdered at Little Horton Private Hire, staff said the dad-of-four would not rest in peace until justice has been done.

The prime suspect is a Jamaican who had arrived in Britain three months before the shooting. Officers are investigating gangster links and think the killer may have fled to London, Jamaica or the US.

They say the killing was linked to an incident in which Mr Basharat clipped wing mirrors with another car on October 19, the day before he was shot.

Detective Superintendent Bob Bridgestock, who is leading the hunt, said the force has done "everything in its power" to catch the killer and a full murder inquiry is being conducted.

Driver Shaokat Khan, 33, was sitting in the Park Lane office when the masked gunman strode in. Without saying a word, the man shot Mr Basharat once in the head and then twice more after he fell to the office floor. He then pointed the gun, a converted gas-powered pistol, at Mr Khan and other staff but the barrel exploded, rendering it useless.

"The last six months have been hard, particularly because the man who did this has not been caught," Mr Khan said. "It doesn't look like the police will get him. I don't think the police have done enough. How can they let the killer disappear like this?

"This man has killed him over a wing mirror - left children without a dad and a wife without her husband. For the sake of Bash's family, he must be caught. It would at least give them that peace of mind and allow his soul to rest in peace."

Det Supt Bridgestock said the investigation centred on a group of Afro Caribbeans staying in Little Horton. Nobody has been charged but 11 people have been arrested and seven sent to Jamaica as illegal immigrants. But one 28-year-old "particular individual" wanted for questioning has not been traced.

Det Supt Bridgestock said that some people with information may now feel able to come forward after the group's expulsion from Britain.

Anyone with information should call (01274) 376485.