CORTE MADERA, Calif. -- The family of a man killed in a Marin County freeway shooting last week has been told that an arrest has been made in the case and that the crime had nothing to do with the Hells Angels procession the victim was riding in last Saturday.

San Leandro resident William MacLean -- described as an associate of the motorcycle group -- was shot while riding in a pickup truck that was leading a funeral procession of Hells Angels motorcyclists through Marin County. The shooting occurred somewhere between the Tiburon exit and Corte Madera.

The 25-year-old Maclean died in hospital shortly after the shooting Saturday night.

On Thursday, the Maclean family attorney claimed that investigators are saying an arrest has been made and that the shooting appears to be a random act of violence.

Attorney Anthony Brass says Maclean was gunned down by a woman in another car and that the incident was possibly triggered by a road rage dispute. He also asserted the shooting was unrelated to Maclean's brother-in-law Raymond Folks, a Hells Angels leader in Sonoma County.

"That's what everyone assumed. I think everyone was looking at it because Raymond Folks is a notorious character and Willie Maclean is his brother-in-law -- that this was Hells Angels related in some way," said Brass.

Maclean's brother-in-law has denied all along that the incident was some sort of "hit."

"Obviously this was emotional for him. He's close to him; he's his wife's brother. He's emotionally involved. But this was a random act and that's what he said from the beginning," said Brass.

The Marin sheriff's department would not confirm or deny that they have the suspected shooter. Representatives would only say that the investigation continues.

The department did say that they plan to beef up law enforcement presence this Sunday when the Hells Angels host an annual ride from Corte Madera to Novato, in case more bikers than usual come to honor Maclean.

"It's a multi-agency situation. Agencies supply additional resources from around the county so we can assure the security of the public and the security of the event," said Marin County Sheriff’s Department Sgt. Keith Boyd.

The family attorney says if more riders show up to honor William Maclean, it will be their individual decision, not on orders from the Hells Angels.

"It is sort of a slap in the face for law enforcement to gear up when these are people who cared about a victim of a random act of violence," said Brass.

The ride usually draws about 200. Deputies are bracing for twice that.