British police have arrested a fourth suspect in their ongoing investigation into the death of a Canadian biker shot dead on a busy English highway.

Gerald Michael Tobin, 35, was riding the M40 through the central England county of Warwickshire when he was shot and killed in broad daylight on Aug. 12, after leaving the Bulldog Bash motorcycle festival -- a Hells Angels biker convention.

Warwickshire police said today that the fourth suspect was arrested late Wednesday night in the Alderman's Green area of Coventry.

Three men were arrested earlier Wednesday and police also revealed that three vehicles had been seized in connection to Tobin's death.

Tobin was born in England but moved to Canada as a boy. After moving back to the U.K. 10 years ago, Tobin worked at a Harley Davidson dealership in south London as a mechanic.

Details of the case

Police have previously said that a green Rover 600 series car, with two or three people inside, started following Tobin and two other motorcyclists as they returned from the festival.

Several kilometres later, the green car overtook two of the three motorcycles and came close to Tobin.

Two shots are believed to have been fired, and one of those struck Tobin on his head just below his helmet.

Tobin fell off his motorcycle, which continued to career another 200 yards down the road.

Autopsy results show Tobin died of a single gunshot wound to the head.

Meanwhile, a number of items, including multiple bladed weapons and one firearm, have been recovered from police searches of the homes of the men arrested.

Police also confirmed that two vehicles, a van and a Rover car, were seized Wednesday.

A second, fire-damaged Rover car was recovered prior to Wednesday's arrests and is also being forensically examined. Police are not releasing details about when or where the vehicle was found.

Police have confirmed that Tobin had no criminal record in the U.K. or Canada.

With files from The Canadian Press