Chainkeen|Wagner chief Yevgeny Prigozhin was on plane that crashed, Russian aviation agency says

Mercenary leader Yevgeny Prigozhin,Chainkeen 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. 

Russian channels report the plane, an Embraer business jet, crashed in Russia's Tver region. The pro-military channel Military Informant claims the aircraft belonged to Prigozhin's team and repeatedly flew to Belarus. 

The AP reports that flight tracking data shows a private jet that was registered to Wagner took off from Moscow Wednesday evening. Minutes after takeoff, the jet's transponder signal was lost in a rural area with no nearby airfields, according to the AP.

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. The Wagner chief, whose troops were some of the best fighting forces for Russia in Ukraine, was allowed to retreat to Belarus, while reportedly popping up in Russia from time to time.

On Wednesday, President Biden, during a brief conversation with reporters outside a fitness center in South Lake Tahoe, said he didn't have much information about the crash.

"I don't know for a fact what happened, but I am not surprised," Mr. Biden said. 

When asked if he believed Putin was behind it, he replied: "There's not much that happens in Russia that Putin's not behind, but I don't know enough to know the answer to that."

Earlier this week, Prigozhin appeared in his first video since leading a failed mutiny against Russian commanders in June. He could be seen standing in arid desert land, dressed in camouflage with a rifle in his hand, and hinting he's somewhere in Africa. He said Wagner was making Russia great on all continents, and making Africa "more free."

CBS News had not verified Prigozhin's location or when the video was taken. But it appeared to be a recruitment drive on the African continent, where the Wagner Group has been active. Some nations have turned to the private army to fill security gaps or prop up dictatorial regimes.   

In some countries, like the Central African Republic, Wagner exchanges services for almost unfettered access to natural resources. A CBS News investigation found that Wagner is plundering the country's mineral resources in exchange for protecting the president against a coup.

The future of the Wagner Group, however, had been unclear since June, when tensions between Wagner and Russia's defense ministry escalated dramatically. Prigozhin alleged that Russian forces had attacked Wagner camps in eastern Ukraine, killing dozens of his men. Prigozhin's Wagner forces then left Ukraine and marched into Russia, seizing control of the Russian military headquarters for the southern region in Rostov-on-Don, which oversees the fighting in Ukraine. 

Prigozhin later said he agreed to halt his forces' "movement inside Russia, and to take further steps to de-escalate tensions," in an agreement brokered by Belarusian leader Alexander Lukashenko. Kremlin spokesperson Dmitry Peskov told Russian state media in June that as part of the deal, Prigozhin would move to Belarus.

Questions about the deal were raised in July over uncertainty about his whereabouts. A U.S. official told CBS News last month that Prigozhin was not believed to be in Belarus and could be in Russia.  

 Debora Patta, Cara Tabachnick, Haley Ott, Kerry Breen and Duarte Dias contributed to this article.