Oz question
 

I was curious if anyone knows what happened to Yuri Kosgygin? He came to the show in Season 3 and then disappered. Does anyone know if an explanation was given for his disapperance and if so what happened? He was actually a good part of the show because he looked like a harmless old man but was one of the most dangers prisoners in Oz.

I looked on this site, but couldn't find an answer of what happened to him.

He's listed under Season 3 Prisoners and was introduced in the "U.S. Male" episode.