Well we'd said the roommate was murdered. Single murder, no one else there unbeknownst to your character.
We'd figure out a way to clear yours after a time, I'm sure, can't have it go on forever. Maybe he's innocent of the murder but doesn't want a specific person to know that he'd been busted on some minor things before? Like underage drinking or a fight or something...? So he doesn't feel entirely innocent?