The head of a Russian mercenary group who launched a rebellion against Moscow’s military leadership in June is presumed dead after a mysterious plane crash.

But much remains uncertain. Here’s what we know and don’t know.

What happened to the plane?

Authorities said the private jet that took off from Moscow and was headed for St. Petersburg was carrying Yevgeny Prigozhin and some of his top lieutenants from the Wagner private military company. It went down northwest of the capital — after what appeared to be an explosion — minutes after takeoff. Everyone on board was killed.

Is Prigozhin dead?

Presumably. There’s been no official confirmation, but Russian authorities investigating the crash found 10 bodies and will use DNA to confirm their identities. President Vladimir Putin expressed his condolences about it.

Is it possible he was targeted?

No one knows — but many are speculating that he was. After Prigozhin staged his short-lived rebellion and Wagner forces made a dash toward Moscow, several U.S. officials had predicted that something like this would happen. Numerous opponents and critics of Putin have been killed or gravely sickened over the years in apparent assassination attempts. Last month, U.S. Secretary of State Antony Blinken said that Russia under Putin had an “open windows policy,” implying the Wagner chief might get thrown out of one.

Is anybody trying to get to the bottom of what really happened?

The Russian government says it is conducting an investigation, though it remains to be seen how much information will be released. Keir Giles, an analyst at Chatham House, warned that the “crash is so politically significant that there is no chance of any investigation that will be either transparent or reliable.”

Who else is thought to have been on the plane?

The passenger manifest is essentially a who’s who of Wagner mercenaries, including its second-in-command, who baptized the group with his nom de guerre, as well as the logistics chief, a fighter wounded by U.S. airstrikes in Syria and at least one possible bodyguard.

What happens now to the Wagner mercenary army?

After Prigozhin’s failed rebellion against Russian military leaders, Putin gave the thousands of Wagner troops in Ukraine three options: join the Russian army, return home, or move to Belarus. The rest of Wagner’s troops are deployed in African countries, and in Syria, where they ruthlessly protect rulers at the expense of the masses — and, in exchange, Russia gets access to ports, natural resources and markets for weapons sales. It’s unclear if that will change.

Is this good or bad for the U.S.?

U.S. officials have been tight-lipped about the crash and what impact it may have on American interests in Ukraine, the Middle East and Africa, citing uncertainty over how Wagner will continue to operate.