Not only in Russia....You overestimate their reach and abilities. The killings are handiwork of the FSB. Troublemakers get eliminated in Russia. This is a known fact. They don't even hide it.
https://en.wikipedia.org/wiki/Poisoning_of_Alexander_Litvinenko
If ever a country wanted to send a message about disagreeing publicly with Putin, poisoning him with Polonium left no doubt about who wanted him dead.

