Russian investigators on Friday detained prominent Russian nationalist Igor Girkin, who had publicly accused President Vladimir Putin and the army's top brass of not prosecuting the war in Ukraine harshly or effectively enough.
The move, reported by his wife, his lawyer and the RBC news outlet, suggests the authorities have wearied of his criticism of what they call Russia's "special military operation".
It follows an abortive mutiny last month led by another outspoken critic, Yevgeny Prigozhin, boss of the Wagner mercenary force, who is still free but has sharply curtailed his own verbal attacks.
Girkin, also known as Igor Strelkov, helped Russia annex Crimea from Ukraine in 2014 and then organise pro-Russian militias who took control of part of eastern Ukraine from Kyiv.
He was also handed a life sentence in absentia by a Dutch court in 2022 for his alleged role in the shooting down of Malaysia Airlines flight MH17 over eastern Ukraine in 2014, with the loss of 298 passengers and crew.
The former Federal Security Service (FSB) officer had been regarded by many as untouchable due to his background and ties to the authorities but had become more outspoken in recent months.
Girkin announced in May that he and others had set up the "Club of Angry Patriots", to enter politics to save Russia from what he said was the danger of turmoil due to military failures in Ukraine.
Asked at the time if he was naive to think he could launch a political movement without the assent of the Kremlin, he said: "I hope you would not call me a naive person."
Urging Putin to hand over to 'someone capable'
In one of his most outspoken tirades on July 18, in a post on his official Telegram channel, read by over 760,000 people, Girkin peppered Putin with personal insults and urged him to transfer power "to someone truly capable and responsible".
In a message posted on Girkin's official Telegram account, his wife, Miroslava Reginskaya, said:
"Today, at about 11:30 a.m., representatives of the Investigative Committee came to our house. I was not at home. Soon, according to the concierge, they took my husband out by his arms and in an unknown direction."
She said friends had told her Girkin had been charged with extremism.
"I do not know anything about my husband's whereabouts, he has not contacted me," she said.
There was no immediate comment from the authorities. Girkin's lawyer told the state news agency TASS that it was not clear why his client had been detained.
RBC, citing two unnamed law enforcement sources, said Girkin's Moscow home was being searched and that he had been detained over a complaint against him made by a former Wagner employee.
Tatiana Stanovaya, founder of the R.Politik analysis firm, said the men who run Russia's law enforcement and power ministries had long wanted to arrest Girkin.
"Strelkov (Girkin) had overstepped all conceivable boundaries a long time ago," she said.
"This is a direct outcome of Prigozhin's mutiny: the army's command now wields greater political leverage to quash its opponents in the public sphere."
Stanovaya said Girkin's detention was a signal that any of the bitterest critics of Moscow's approach to the war could face prosecution.