Prigozhin has not been seen publicly since Saturday, and reports say the case against him remains open.

Yevgeny V. Prigozhin, the leader of the Wagner mercenary group who mounted a brief uprising against Russia’s military command over the weekend, has not been seen in public since calling off his mutiny on Saturday, adding to the confusion surrounding an episode that has challenged Russia’s veneer of political stability.

Dmitri S. Peskov, the Kremlin’s spokesman, had said on Saturday that under a deal to end hostilities, Mr. Prigozhin had agreed to leave Russia for neighboring Belarus. In return, Mr. Peskov said, the investigation into Mr. Prigozhin and the charges against him for launching the armed rebellion would be dropped.

But according to Russian media reports published on Monday, the criminal case against Mr. Prigozhin remains open and the charges against him have not been dropped. Kommersant, a Russian newspaper, and the country’s three main news agencies — Tass, RIA and Interfax — all reported that the Federal Security Service, or F.S.B., continued to investigate.

The publications, all either state-controlled or affiliated with the Kremlin, cited anonymous sources, so their reports could not be independently verified. If the proceedings continue, Mr. Prigozhin could face up to 20 years in prison.

Mr. Prigozhin was last seen publicly smiling and shaking hands with supporters when he left the southern Russian city of Rostov-on-Don on Saturday night, after he called an end to his brief uprising against the military leadership and turned back the column of soldiers he had sent on a march to Moscow.

Videos of Mr. Prigozhin’s departure from Rostov-on-Don, where Wagner troops briefly seized a military installation on Saturday, emerged shortly after Aleksandr G. Lukashenko, the autocratic leader of Belarus and a dependable ally of President Vladimir V. Putin of Russia, announced he had mediated the deal to end the hostilities. Many observers have raised doubts over whether Mr. Prigozhin would be safe in Belarus, given the government’s close ties to Mr. Putin.

Since then, his whereabouts have been unknown, and Mr. Prigozhin, who has been often profanely outspoken on social media channels throughout Russia’s war in Ukraine, has not commented publicly about departing for Belarus. On Sunday evening, Mr. Prigozhin’s press service told RTVI, a Russian TV channel, that he “says hi to everyone and will answer questions” when he has good cellphone reception.

On Saturday, during a raid of the five-star Trezzini Hotel in St. Petersburg, which is owned by one of Mr. Prigozhin’s companies and believed to be the site of one of his offices, local news outlets reported that police officers had found billions of rubles, packs of an unidentified “white powder” and gold bars.

On Saturday, before he brought the mutiny to an end, Mr. Prigozhin acknowledged that he was in possession of large amounts of cash. The money, he said, was used to pay the wages of Wagner troops and to compensate relatives of Wagner fighters killed in action in Ukraine, a sum that amounts to five million rubles per family (about $59,000).

“For 10 years, Wagner operated on a cash-only basis,” he said in an audio recording. “When we were working in Africa, Ukraine and other countries, when we were scaring America, everyone was happy with cash,” he said, an apparent reference to a troll farm he has admitted using to meddle in U.S. elections. “And now they’re here to search. It’s OK. The cash was actually found.”

Despite the severity of Mr. Prigozhin’s actions over the weekend, which Mr. Putin labeled treason, some Russian officials have been reluctant to criticize Wagner fighters, who have proven themselves to be effective, if brutal, in fighting on Russia’s behalf in Ukraine and other conflicts.

Andrei Kartapolov, the chairman of the Russian Parliament’s defense committee, said Sunday that the Wagner fighters who took over the army headquarters in Rostov-on-Don “did not do anything reprehensible” and had simply “followed the orders of their command.”

“They didn’t offend anyone, they didn’t break anything,” he said. “No one has the slightest claim against them — neither the residents of Rostov, nor the military personnel of the Southern Military District, nor the law enforcement agencies.”