Convictions (http://gedry.livejournal.com/225149.html) by Gedry is really good.

Summary: Dean makes a living in high class home invasion. Dean's careful, he never wanted anyone to get hurt. But when he discovers Castiel still at home while he and his team are robbing the house everything changes. Dean pays the price for his misdeeds but somehow, along the way, he manages to make a friend out of Castiel. A man still struggling with his own kind of incarceration. Their relationship offers Dean some comfort, but once he's done serving his time questions still remain. Are they friends, or something more? Can they make a life together out of the ashes of their old ones, or are they both still serving their sentences?

I have been looking for this exact story for 3 days!!!! I came to storyfinders hoping some one else had been looking for it. I should've remembered it was by gedry cause she is always full of awesome! Thanks for recommending it so I could find it again. -K:-)

Try princess_aleera's mute!Cas verse. (http://princess-aleera.livejournal.com/152759.html)

Seems to fit your request perfectly.