Dorenko was on his motorcycle when he suffered a ruptured aorta and crashed into a traffic barrier, according to Govorit Moskva, a radio station he founded in 2014, citing a coroners’ report.

The crash occurred shortly before a Victory Day fireworks display was to be held in Moscow to commemorate Russia’s defeat of Germany in World War II.

The timing of the crash raised questions in some quarters about whether he had been targeted by officials. Recent deaths of Russian media and political figures connected to the politics of the 1990s have prompted similar speculation that they were killed, possibly because of secrets they may have held.

As a broadcast commentator in the 1990s, Dorenko had supported Putin and pilloried his opponents so effectively that he earned the “TV killer” nickname.

But when he later challenged the Russian government’s stumbling response to the Kursk nuclear submarine disaster in 2000, in which 118 servicemen died, he lost his job.

On the day he died, Dorenko, who had reinvented himself on radio as a commentator and talk show host, posted a barbed comment on social media referring to the Victory Day parade.

“I find a lot of symbolism in the fact that the police and gendarmerie are especially conspicuous at the parade,” he wrote. The post recorded more than 200,000 page views.

Sergei Leonidovich Dorenko was born Oct. 18, 1959, in Kerch, Crimea, to a Soviet military pilot and a librarian. He graduated from Patrice Lumumba Peoples’ Friendship University in Moscow with a specialty in translating Spanish and Portuguese. From 1982-84, he worked as a translator in Angola, according to a biography on the website of Tass, the Russian news agency.

After military service, Dorenko joined state-run Soviet Central Television in 1985, just before censorship policies were being relaxed under President Mikhail Gorbachev’s glasnost program.

But as the Soviet Union began to crumble in 1991, Dorenko was nevertheless fired for his unvarnished reports on Soviet crackdowns in Lithuania and Latvia after they had declared independence.

With the collapse of the Soviet Union later that year, he returned to the air on newly established Russian television channels, including ORT, where he became known as an acerbic commentator. But again he was fired, this time in 1995, after broadcasting a report on President Boris Yeltsin’s shaky health as concerns grew about his electability in the 1996 presidential election. ( Yeltsin won re-election anyway.)

Dorenko was not gone for long, however. In 1996 he returned to ORT, a television station created and controlled by billionaire Boris Berezovsky. In 2013, Berezovsky was found dead under mysterious circumstances in London, where he had been based after a falling out with Putin.

It was at ORT that Dorenko, as host of a weekly current affairs program, played a role in the rise of Putin, a former KGB agent who became prime minister under Yeltsin and ultimately succeeded him when Yeltsin unexpectedly resigned in 1999.

Dorenko reliably attacked Putin’s most viable opponents, including Yuri Luzhkov, Moscow’s powerful mayor at the time, and Yevgeny Primakov, who had been prime minister, foreign minister and foreign intelligence chief under Yeltsin.

In one report, Dorenko portrayed Primakov as a stooge of the North Atlantic Treaty Organization and said that NATO’s goal was “for Putin to resign and to bring Primakov to power.”

By August 2000, however, it was Putin’s turn to be on the receiving end of Dorenko’s frank commentary. In a report on the Kursk submarine disaster, in which the vessel sank in the Barents Sea after an explosion, Dorenko played footage of Putin trying to explain away the response of Russian officials, who had lied about the incident for days.

After reporting on one misleading official account, a stone-faced Dorenko — he almost never smiled on the air — told viewers point blank, “That’s not how it happened.”

“The main conclusion is that the authorities do not respect any of us,” he said. “That’s why they lie.” It was his last nationwide television broadcast.

In the 2011 interview, he said that after the Kursk report, he was told “that I had gone mad, lost it and was a traitor.”

“Everyone recoiled from me as if I was sick,” he said. “It was a frightening period.”

By 2005, however, he had bounced back again, this time as a radio journalist, for Govorit Moskva, where he was the editor-in-chief and hosted a morning show.

His death brought tributes from many liberal Russians but also a rebuke from Viktor Shenderovich, a satirist whose puppet show had been pulled off the air after it mocked Putin. He said of Dorenko on Facebook, “Scoundrels can be charismatic, there is nothing new in that.”

Dorenko’s survivors include his second wife, Yulia; their two daughters, Varvara and Vera; and two daughters, Yekaterina and Ksenia, and a son, Prokhor, from his first marriage, which ended in divorce.

This article originally appeared in The New York Times.