Is there anyway that you can get some closer pictures, both of the top and the bottom (plastron) of the tortoise? Somebody may be able to ID from what you have, but I think it is going to be a little difficult.
At first glance it looks like a Russian, but I am not 100% sure.
If we can tell what it is, we can help you get it set up in a proper house and help with what he is supposed to eat.
Where did you get it? They didn't know what it was?