A Kremlin loyalist suddenly turned against Putin. A day later, he was in a psychiatric hospital.

A loyal pro-Kremlin blogger who unexpectedly denounced Russian President Vladimir Putin as “a war criminal and thief” has been admitted to a psychiatric facility.

Ilya Remeslo, a lawyer and pro-Putin firebrand, shocked both Kremlin supporters and critics Tuesday when he shared a long post on Telegram, titled “Five reasons why I stopped supporting Vladimir Putin.”

Among his reasons, he outlined Russia’s invasion of Ukraine, which he called an “absolutely dead-end war.” He also blamed the Kremlin for “enormous damage to the Russian economy and the well-being of citizens” and criticized the Russian government’s campaign to throttle internet and digital freedoms, including the anticipated ban of Telegram, the country’s most popular messenger app.

Remeslo, previously known as a vocal critic of the late opposition leader Alexei Navalny who even testified against him in court, accused Putin of being in power for too long, with apparent plans “to sit on the throne for at least 150 years.”

Even a “morally impeccable person” would be corrupted by such a long reign, he said.

Putin does not respect his voters and does not want to listen to them, Remeslo wrote, adding that the Russian leader has wiped out opposition, and that anyone who has dared to speak out is either in exile or dead.

“Bottom line. Vladimir Putin is not a legitimate president. Vladimir Putin must resign and be brought to trial as a war criminal and thief,” he wrote.

Remeslo’s comments were an unusual public display of dissent and personal criticism of Putin in an atmosphere of repression and tight control in Russia, exacerbated by the invasion of Ukraine.

So abrupt was the change that some in the pro-Kremlin camp speculated that Remeslov’s account might have been hacked, that he was being held hostage or that he had for some other reason just lost the plot.

Remeslo responded in posts on Telegram that he had not been hacked, that he remained in Russia and stood by his opinions.

On Wednesday, he continued his criticism, accusing Putin of an “insane, borderline morbid craving for luxury” as he referenced anti-corruption investigations into the leader’s assets, of the kind pioneered by Navalny.

He also recorded a video saying that Putin was too afraid to surround himself with those who can tell him the honest truth.

In a response to the Russian media outlet Ostoroghno Novosti, Remeslo said his views changed because the country has “changed a lot.”

Prominent pro-Kremlin TV host Vladimir Solovyov discussed Remeslo on his show Wednesday, referring to him as “a lawyer who has lost his mind,” without naming him, saying “some people’s nerves can’t take it.” Responding to Solovyov’s criticism, Remeslo urged him to switch to the “side of light.”

Meanwhile, some opponents of the Kremlin expressed doubts about Remeslo’s motives, and whether he had already fallen out of favor with the Kremlin.

But the story took a dramatic turn after Remeslo abruptly stopped posting late Wednesday.

On Thursday, the news website Fontanka reported that Remeslo has been hospitalized at Skvortsov-Stepanov Psychiatric Hospital No. 3 in St. Petersburg.

When NBC News called the hospital Friday, a man who picked up the phone but did not want to share his name said that someone matching the name of Ilya Remeslo was indeed a patient at the hospital. He was admitted Thursday, but the grounds for his hospitalization can only be revealed to the patient’s family, NBC News was told.

Remeslo did not respond to a request for comment.

The blogger, 42, was previously a vocal critic of Navalny, who died in an Arctic penal colony in early 2024. The state news agency Tass called Remeslo “one of Navalny’s most famous whistleblowers” as he testified against the politician in court in 2022 and investigated his anti-corruption fund, FBK.

In one of the posts Wednesday, however, he signed off with a tagline made famous by the late opposition leader, concluding: “Here we tell the truth.”