I’d never heard of the man but I find this sort of thing intriguing and know many dopers are knowledgeable. Here is a snippet from a Reuters article that seems to imply that it wouldn’t be out of the question.
edit: there is bio info in the article. Briefly, he was a Russian billionaire living in London who for over 10 years was one of Putin’s harshest critics.
I doubt it. But if you’ve never heard of him: he was one of the infamous oligarchs — misnamed since they were not a governmental elite – who robbed Russia blind.