Russian minister dies hours after being sacked by President Vladimir Putin (www.lbc.co.uk)

Well, afaik, he was connected to a massive corruption case that involved defence of russian territories in Kursk. He was being investigated. So he was not a great man.

Idk if it really was a true self-elimination, but if it was, he probably did it to avoid prison. Russian prisons are notoriously harsh.

If he was taken out by somebody else, then he probably knew too much or crossed somebody in russian elite.

People usually tend to blame it all on russian government, but I am not inclined to do so. Russian government would be fine with just putting him behind bars – much less noise and even an image boost (look, we are fighting corruption).
So it probably was not the government – if that was indeed foul play, that is.