As for what happened... it's rumored that his best friend in the world and teammate committed suicide with his rifle when he was out of town. The Police report said suicide with teammate's gun, and I believe the report said the gun owner didn't have knowledge nor gave him permission to borrow the gun.
The rest is a bit of speculation, but Madison was known for "always" going hunting when given the chance and had weapons, and being best friends, they might of had access to each other apartments (or knew where a key or open window was).
If this rumor is true, it might of set something negative off in his mind, and he might have negative thoughts roaming around, especially with something that reminds him of his best friend or teammate, so I think it's possible he be done for good, or who knows, he might be best next season.
But even if he comes back, he's not a lock to make the roster much less be a lock to be good enough to start. So I wouldn't act as he's not a sure thing.