There have been many high profile murders and attempted murders on behalf of Putin. Three are:
Viktor Yushchenko: Ukraine—poison—failed
Anna Politkovskaya: Russian journalist—murdered
Alexander Litvinenko:ex-soviet spy—radiation—successful
To quote one of my favorite Founding Fathers:
“...I have but one lamp by which my feet are guided, and that is the lamp of experience. I know of no way of judging of the future but by the past.... “
It is not tinfoil to speculate anything given the fragile state of the world today.
The Russia government has been in the murder/assassination business for many decades.