(NewsNation) — The Pentagon said it is “likely” Russian mercenary leader Yevgeny Prigozhin was killed in a plane crash caused by an intentional explosion onboard.

But there has been no official confirmation of Prigozhin’s death. In 2019, Prigozhin was reported dead in a plane crash in Africa, only to resurface three days later.

Former KGB agent Jack Barsky said there are still more questions than answers, and “we may never know the truth” about what happened. However, he said there’s “no way” Prigozhin or his men supposedly onboard wouldn’t have checked the plane for a bomb.

“These guys were some of the most ferocious warriors and extremely well trained,” Barsky said Thursday on “Elizabeth Vargas Reports.” “They don’t make such stupid mistakes.”

Prigozhin was the head of the Wagner private military group Russia has used in Africa, Syria and Ukraine.

He and six other passengers were on a private jet that crashed Wednesday soon after taking off from Moscow with a crew of three, according to Russia’s civil aviation authority. Rescuers found 10 bodies, and Russian media cited anonymous sources in Wagner who said Prigozhin was dead. Currently, there has been no official confirmation.

It was not clear why several high-ranking members of Wagner, including top leaders who are normally exceedingly careful about their security, were on the same flight. The purpose of their joint trip to St. Petersburg was unknown.

“He and his group was very security conscious. There’s no incident where there are high-level people of the Wagner group on the same plane,” Barsky said.

President Joe Biden, speaking to reporters Wednesday, said he believed Russian President Vladimir Putin was behind the crash, though he acknowledged that he did not, at that time, have solid information verifying his belief.

Earlier this summer, Prigozhin led a short-lived rebellion against Putin, marching hundreds of miles from southern Russia toward Moscow in a show of grievance over the Russian military’s handling of supplies and living conditions for Wagner troops.

The convoy turned around before it reached Moscow, and Prigozhin went to Belarus.

If the Russian president did indeed greenlight an assassination plot, Barsky said the scheme would have been a closely held secret by a small group of people within the G.R.U, the Russian military intelligence agency.

“The Russian intelligence inherited their DNA from the KGB, and the one thing that the KGB was very, very good at was compartmentalization and keeping the number of people that know something very small, so that when Putin comes out and makes a statement, there’s not a single person who is both knowledgeable and is also brave or fundamentally suicidal to contradict Vladimir Putin in public,” Barsky said. “That’s the only way this kind of thing could have been planned and executed.”

In this first comments on the crash, Putin said the passengers had “made a significant contribution” to the fighting in Ukraine.

“We remember this, we know, and we will not forget,” the president said in a televised interview with the Russian-installed leader of Ukraine’s partially occupied Donetsk region, Denis Pushilin.

Putin recalled that he had known Prigozhin since the early 1990s and described him as “a man of difficult fate” who had “made serious mistakes in life, and he achieved the results he needed — both for himself and, when I asked him about it, for the common cause, as in these last months. He was a talented man, a talented businessman.”

The Associated Press contributed to this report.