Is there any more background information about Belcheck?

In the 12 episode 24 revival 24: Live Another Day Jack Bauer is supported from the begin on by some dubious Eastern European associate named Belcheck ("Just one word. Like Madonna."). He stays a mystery throughout the entire season, helping Jack all along without asking questions or giving much commentary. All that I remember him saying about himself though, is that he once was helped by Jack and seems to be in somewhat of a debt to him.

Now it might be very well that he is intentionally kept a mystery, as part of Jack's rather unclear 4 years in the underground. Yet I also don't have much of a detailed recollection of the previous seasons and don't know if he maybe makes an appearance there. Or maybe I just missed some additional hints from this season or there is additional material, similar to the movie set between seasons 6 and 7. So is there any more background information about Belcheck from any other 24 material or at least additional reasonable deductions to be drawn from this season?