Who killed Litvinenko?

The media is again attacking Putin by bring up the death of Alexander Litvinenko.  Litvinenko was a critic of Putin but I don't think Putin kill him.  I am no Putin fan but I think Goldfarb, a Soros man, had the nuclear chemistry background and I think was Litvinenko's handler. If I was a KGB agent using Polonium 210, I wouldn't leave a contamination trail all over London. 

Also, Google deleted my previous post on this without notifying me.