Radiation poisoning? Seems to be a Russian favorite means of asssassination in the last decade or so, in fact Edit actually I didn’t realize Litvinenko was the same famous case I considered part of a bigger trend and I don’t see other cases after a quick Google. Disregard my comment, with my apologies. I thought I remembered a larger pattern. That said, more generic poisoning does seem to be a pattern: https://www.google.com/amp/s/timeline.com/amp/p/4256eafcd76c