There are anti-Putin mafia groups in Russia. It's plausible that they would have contacts within the prison population.
Offing Navalny (a' la Tom Hagen with Frankie Pentangeli) would be more advantageous politically to the mobsters than anything he could have accomplished alive, with his sub-5% approval rating in Russia (of course, 99% in the west).
see my post #26
Sure, and did these supposed "anti-Putin groups in Russia" poison Navalny in 2020 with Novichok nerve agent?
Did these supposed "anti-Putin mafia groups" sentence Navalny to 33 1/2 years in prison and send him to the Russian Arctic prison IK-3, a penal colony infamous for its brutal conditions about 40 miles north of the Arctic Circle.
Navalny might have joked about prison, but the reality of life in IK-3 was brutal
According to the BBC, Polar Wolf enforces a culture of collective punishment on its inmates.
For example, prisoners have been forced to stand out in the winter cold without any coats. During the hot summer, inmates have been forced to go shirtless when prison grounds were teeming with mosquitoes, the BBC reported.
"Conditions there are extremely harsh because the special regime is essentially legalized torture," an unnamed lawyer told Meduza, an independent media outlet in Riga, Latvia, in a story published Friday.
Lookie here, logic applied to back an opinion. This would be like Biden killed Chris Christie, because he was a political threat.