An old associate of Russian President Vladimir Putin who was demoted after publicly criticising the Kremlin leader has died from an unexplained " serious disease ".
Viktor Cherkesov, once Putin's trusted deputy and the former chief of the Federal Drugs Control Service (FKSN), has died aged 72.
Cherkesov was once in charge of crushing Soviet dissidents and was instrumental to the Russian president’s rise, but the pair later had strained relations.
When Putin headed the FSB secret service before becoming prime minister, Cherkesov was installed as his trusted deputy.
Earlier he had been in charge of law and order in St Petersburg when it became Russia ’s “criminal capital” with a record for countless unsolved contract killings.
At the time, Putin was deputy mayor.
No further details were immediately given on Cherkesov’s cause of death in St Petersburg.
In 2007, Cherkesov had suggested in a newspaper that the secret services were becoming corrupted under Putin.
Instead of being “warriors”, senior officers were enriching themselves as “merchants”, he warned.
An outraged Putin subsequently hinted his longtime ally Cherkesov was hardly clean and said he "considered it incorrect to air such problems in the media".
“And if someone acts in this way, makes such claims about a war of the special services, he himself must first be impeccable.”
At the time an agent and also a former agent working for Cherkesov - then Director of the Federal Drug Control Service - died mysteriously from "poisoning".
Cherkesov was fired from this role in the wake of his criticism of the secret services under Putin.
Some interpreted his demise and the poisonings as due to brutal turf wars among Putin’s warring henchmen.
Yet Putin did not want to lose him completely.
Cherkesov - seen by one source as “knowing where the bodies are buried over many years” - was made Head of the Federal Agency for the Supply of Weapons, Military, Special Equipment and Materials for a two year stint.
He later became an MP, but was never again seen as being in Putin’s inner circle, even though the men had been close since university.
Yet he was described as “one of the few people with whom Putin is frank”.
Cherkesov was deputy head of the FSB at the time of apartment block explosions in September 1999 in the Russian cities of Buynaksk, Moscow and Volgodonsk, in which 300 died, and a near miss in Ryazan, where a device was disarmed.
The FSB blamed the attacks on Chechen terrorists but independent journalists claimed the secret services was behind them in a political ploy to aid Putin.
Putin - then PM - used the “terrorist threat” to wage a “popular war” in Chechnya which helped him secure the presidency for the first time in 2000.
Unlike many other old Putin cronies, Cherkesov was not seen as flamboyantly cashing in on his connections, and was not listed as a billionaire.
Cherkesov was a colonel-general in the reserves and a retired police general as well as an honoured lawyer and “honorary counterintelligence officer”.
His second wife Natalya Chaplina, 65, runs a news agency with close links to the Russian security services.
He had been in charge of the KGB unit responsible for combating anti-Soviet propaganda in the 1980s.
