"I will die within a year"
He's a Tom Clancy fan, then ?
Seriously though, although I am ready to believe that CIA agents are perfectly capable of killing a high-profile, wanted individual of any nationality if there is a need, if he was in such danger from US spymasters he might have wanted to avoid going to a US-extradition-friendly country in the first place ?
When you play the game, you play it all the way. If you are aware that you have information that is so badly wanted by a given country, you plan your life around avoiding getting caught by that country.
The fact that he did not do so signifies that his claims are rather on the bogus side, or at least that he is not the professional spy he thinks he is.