A fourth man has been arrested in connection with the fatal shooting of a Hells Angel biker on the M40 motorway.
Gerry Tobin (35) was shot in the back of the head as he rode home from an annual biker event, the Bulldog Bash, in Warwickshire on August 12th.
The latest arrest took place in Coventry on Wednesday evening and follows the arrest of three men earlier in the day after raids on addresses in Coventry and Nuneaton.
Searches of premises are continuing, and several items have been seized.
Police have received more than 600 calls and e-mails from the public in response to appeals, and they are still urging anyone with information about a dark-coloured Rover 600 car to come forward.
Detectives believe Mr Tobin, a motorbike mechanic who lived in south London, had been deliberately targeted after being followed from the event.
They said it was possible he had been targeted by a rival bikers' gang.