O'Brien -- who keeps in touch with Miller and last talked to him a few weeks ago -- tells us, "He's a great kid. Comes from a good family. Cares about people. That's not the kid I know. It doesn't sound like something he'd do."
Coach O'Brien says his primary concern right now isn't Miller's football career (he was cut by the 49ers) ... it's his life.
"He's facing some serious charges. I hope he gets this settled so he can move on with his life."