If so, and it was a biker, the cops would have a get out of jail free card - cops initiated or no reason for all the "issues" with the case.
One of the issues is the presence or absence of probable cause for conspiracy, applied to all those arrested.
It is also possible for there to be a wrongful death against law enforcement, even if a biker or several bikers started the violence.
There is also a general issue that the police could have prevented the altercation entirely, by arresting conspirators before violence erupted.