Hunt for Hell's Angel's motorway killer hindered by bikers' wall of silence

The images show Gerry Tobin, 35, relaxed and smiling as he stopped to buy fuel at a petrol station.

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Twenty mintues later he was shot in the back of the neck as he rode home from the Bulldog Bash bikers' festival in Warwickshire on August 12.

Detectives thought his killer only fired once.

But today they revealed that the unknown attacker had taken a second shot from a green Rover 620, which hit the mechanic's motorbike as he travelled along the M40.

At a press conference this morning, police also released the CCTV footage and made a new call for help in solving the murder.

Detective Superintendent Ken Lawrence, who is leading the investigation, appealed for "quite a few" motorists who stopped on the motorway after the shooting before driving off to come forward.

He also made a direct plea for members of the Hell's Angels motorcycle club to give the police more help in their inquiry.

"I'm concerned that the Hell's Angels are not coming forward and sharing what information they have with me," he said.

"I'm sure they will have theories about Mr Tobin's death and I'm asking them to share those with the police.

"I would like to enter into a meaningful dialogue with them but they are reluctant to do that."

The murder has prompted fears of a violent feud erupting between rival motorcycle gangs, but Mr Lawrence urged bikers not to take the law into their own hands.

"I would say, don't even consider any retaliation - that would be entirely wrong," he said.

"The law must deal with this."

Police have received more than 500 calls from members of the public with information about the incident, and Mr Lawrence urged motorists who were on the M40 last Sunday afternoon to report anything they might think important, no matter how trivial it may seem.

Mr Lawrence said that while it was difficult to be 100% certain, he was "content" that the fatal shot was fired from a green Rover 620 seen passing Mr Tobin at the time.

Motorists reported seeing the Rover driving off at great speed immediately after the attack.

Officers are studying CCTV footage including images of the Rover.

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Mr Lawrence said the priority for the police now was to establish the motive for Mr Tobin's murder.

The murdered biker's mother has travelled from Canada to help police build up a picture of Mr Tobin's character and past life.

Last week, his distraught girlfriend Rebecca Smith paid tribute to her partner of five years.

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She said: "Gerry was a thinking man, always ready and able to offer guidance and support to others, a true inspiration to many people, a charming personality whose quick-witted humour always kept everyone smiling.

"The nature of his untimely death due to a callous and cowardly act of violence from which it was impossible to defend himself, only accentuates further the pain and suffering that we are all experiencing due to this terrible loss."