One notable case is the poisoning of the defected Russian spy Sergei Skripal and his daughter in the UK in 2018. The police investigation identified two people from the Russian military intelligence service.
Sixteen years ago, the investigative journalist and critic of the regime, Anna Politkovskaya, was poisoned.
She fell ill quickly and ended up in a coma, but survived and continued to work as a journalist until she was brutally murdered outside her home two years later.
The Kremlin claims that Russia has not received any evidence that Navalny was poisoned and denies that the Russian state is involved.
In the video you can see three examples of previous poisoning scandals.