Let me look in my crystal ball...

...white or Hispanic male, jeans, boots, facial hair, black clothing.

In all seriousness though, the cops aren't gonna post the info and try to get the guy. In the interest of public safety it will all get turned over to the Feds and maybe in four years the guy gets arrested after god knows how many more crimes or murders. An unsolved biker gang murder gets alphabet soup agency funding---some fuckhead who turns himself in or is quickly apprehended and sentenced to life...doesn't.

This is the kind of stuff that Leo's can make a career on, they don't want to simply catch the guy and waste all that opportunity. More than likely the trigger man will become a paid informant, make hundreds of thousands if not millions (yes six zeros) from whatever fed agency and they will get a bunch of small fish and claim victory while the guy who is crazy enough to murder people in public gets rich, gets a new life, and a clean record.

Google hells angels Michael Kramer. Or hells angels Thomas big red Bryant. Or who knows how many others.