He wasn't imprisoned, they sent him to the asylum for 8 years because claiming German banks could do criminal things is just such crazy of a thing to do.

Which has quite some similarities to what happened to Hessian tax investigators [0] that were too successful for their own good: Using psychiatric assessments to discredit people who blow the whistle on corruption.

In that context it's quite cynical how nearly every high-profile suicide in Russia is framed as some kind of political hit-job ordered straight by the government, while in other countries people are looking for any reason to deny the existence of foul play.

[0] https://de.wikipedia.org/wiki/Steuerfahnder-Aff%C3%A4re