Transfermarkt lists a player named Mark Russell as being with FK Vojvodina in Serbia and says he is American. The club site doesn't list him, though he could be a new signing. That said, I don't know who this would be. There is a player of this name who has played recently in Ireland (for Ferrybank) but I have no idea if this is the same guy, whether he's American, or if he's even in Serbia at all. Just wondering if anyone has any ideas.
You can find some info (in Serbian) on this page... scroll down a little. http://www.firmanovisad.net/fkv-forum/viewtopic.php?t=544&start=1365
Actually, that's really useful -- as it seems to indicate that the guy we're talking about is actually Mark Conrad, who played for the University of Puget Sound. He's a big striker from Washington State and, apparently, loves the camera: http://www2.ups.edu/athletics/msoccer/2007/players/mconrad.html
I don't really speak Serbian, but I believe he said his mom is Dutch. Some words look similar to Czech.