There are other logical explanations as well, but I won't point them out because it could ruin it, assuming Fox is town.
I don't think the mafia would claim doc because they can risk having a member outed to wait another night to kill Ely, even if Ely does out a scum, it's still a 1 for 1 trade, worst case scenario for them. If Fox was mafia, claiming doc, and this is a ploy, it's still 1 for 1, best case scenario. They get no benefit out of it, so unless Fox made a mistake as mafia, I would guess he's town. A 1v1 trade with Ely and a mafia is not worth it as we know that there is a backup investigator somewhere.
Either way, if Ely turns up dead tonight, we can lynch Fox. A 1v1 trade for us is likely very good.
---------- Post added 2013-06-13 at 01:44 AM ----------
Anyways, it's getting close to 2am here, and my family is loud enough in the morning that they'll wake me up, so I need to sleep.