Maybe a darker shade of gray? It looks more like a casual shirt than anything.
And aren't prison clothes usually black and white stripes?
Maybe once they finish the jail, once you get sent, you are automatically put in either that or a orange jumpsuit like outfit plus your original head, and it sticks for 48 hours after your release. That'd be cool, because even though you just got out of jail, it'd make the player seem more BA.