Assuming one person had the gun and made the decision, and everyone else went for the ride... State can definitely charge him with something that will result in prison time if he was in the car during the murder that happened a month ago.
The time to come forward was that week. No one wants to be a snitch, he chose to hide it. But when you have stupid criminals as friends, this stuff happens. Now he has the lawyer to offer his testimony and get off light, maybe even avoid a charge.
The problem with the scene is too many were present. Someone is going to turn in everyone, Joseph is going to beat them with his money and good legal advice.
You have to cut ties with the boys. They don't have the same things to lose. They think you're still down for shoot outs, drug deals and whatever else is normal in their world and they don't have enough decency to realize they're %#*$# up your world.
Even if he avoids charges, he still gets suspended for a long time. Hopefully it wisens him up and he chooses to change direction in life for the better. Will stink if it's on another team, cause dude definitely has talent.