The idea that every suspicious death happening in russia is because of Putin has always been nonsense. Russia is filled with gangsters who have the ability to kill you if you get in their way. Only in the case where exotic materials like polonium and novichok etc are used can you be sure that Putin was involved. And even that is not 100%, this is russia, everything is available for the right price.
If you are a journalist uncovering corruption, you will run into an oligarch is angry at you well before you even show up on Putin’s radar. If you are poking around near chechen matters, Kadyrov will send his goons to terminate you. Then you have the russian mafia etc. More shit like FSB guys moonlighting as hitmen. All these guys are interlinked in one big web, and which side ends up killing you depends only on which thread you randomly ended up pulling.