Mercenary leader Yevgeny Prigozhin, who led a brief armed rebellion against the Russian military earlier this year, was aboard a plane that crashed north of Moscow on Wednesday, killing all 10 people on board, according to Russia’s civil aviation agency.

The crash immediately raised suspicions since the fate of the founder of the Wagner private military company has been the subject of intense speculation ever since he mounted the mutiny. At the time, President Vladimir Putin denounced the rebellion as “treason” and a “stab in the back” and vowed to avenge it. But the charges against Prigozhin were soon dropped, and the Wagner chief was allowed to retreat to Belarus, while reportedly popping back in Russia from time to time.

The crash also comes after Russian media reported that a top general linked to Prigozhin was dismissed from his position as commander of the air force.

A plane carrying three pilots and seven passengers that was en route from Moscow to St. Petersburg went down almost 300 kilometers (185 miles) north of the capital, according to officials cited by Russia’s state news agency Tass.

Russia’s civilian aviation regulator, Rosaviatsia, quickly reported that he was on the manifest and later said that, according to the airline, he was indeed on board.

Earlier, Vladimir Rogov, a Russia-appointed official in the partially occupied Zaporizhzhia region in Ukraine, said he talked to Wagner commanders who also confirmed that Prigozhin was aboard. Prigozhin’s top associate, Dmitry Utkin, whose call sign Wagner became the company’s name, was as well, according to Rogov.

“We have seen the reports. If confirmed, no one should be surprised,” said U.S. National Security Council spokeswoman Adrienne Watson said in a statement.

Keir Giles, a Russia expert with the international affairs think-tank Chatham House, had urged caution about reports of Prigozhin’s death. He said, “Multiple individuals have changed their name to Yevgeniy Prigozhin, as part of his efforts to obfuscate his travels.”

“Let’s not be surprised if he pops up shortly in a new video from Africa,” Giles said.

Flight tracking data reviewed by The Associated Press showed a private jet that Prigozhin had used previously took off from Moscow on Wednesday evening and its transponder signal disappeared minutes later.

The signal stopped suddenly while the plane was at altitude and traveling at speed. In an image posted by a pro-Wagner social media account showing burning wreckage, a partial tail number matching a jet previously used by Prigozhin could be seen.

Videos shared by the pro-Wagner Telegram channel Grey Zone showed a plane dropping like a stone from a large cloud of smoke, twisting widely as it fell. Such freefalls can occur when an aircraft sustains severe damage, and a frame-by-frame analysis by The AP of two videos was consistent with some sort of explosion mid-flight. The images appeared to show the plane was missing a wing.