The plane carrying Prigozhin seemed fine on radar until a 'sudden downward' drop in its last 30 seconds

• A plane crash in Russia on Wednesday killed 10 people on board. Yevgeny Prigozhin is presumed dead.
• It plummeted suddenly after appearing fine on radar, a flight-tracking expert told Reuters.
• Some have speculated that air defenses shot down the plane.

The plane carrying Yevgeny Prigozhin, the mercenary who rebelled against Vladimir Putin, showed no signs of trouble on radar before a steep drop in the last 30 seconds of its flight, Reuters reported.