MOSCOW (AP) — Russian President Vladimir Putin said Thursday that hand grenade fragments were found in the bodies of people who died in the Aug. 23 crash of mercenary chief Yevgeny Prigozhin’s plane.

Experts investigating the crash found no indication the private jet had suffered an “external impact,” he said. Prigozhin and two of his top lieutenants of the Wagner private military contractor were among the 10 people killed when the jet came down as it flew from Moscow to St. Petersburgh.

There was no way to independently verify Putin's statement.

A preliminary U.S. intelligence assessment concluded that an intentional explosion caused the crash, and Western officials have pointed to a long list of Putin foes who have been assassinated. The Kremlin called allegations he was behind the crash as an “absolute lie.”

A Russian investigation was launched but no findings have been released. Moscow rejected an offer from Brazil, where the Embraer business jet was built, to join the inquiry.

While Putin noted the probe was still ongoing and stopped short of saying what caused the crash, his statement appeared to hint the plane was brought down by a grenade explosion.

Prigozhin’s aborted rebellion in June marked the most serious challenge to Putin, who has been in power for more than two decades. The crash came two months to the day after the rebellion’s start.

Putin also noted that while investigators haven’t tested the remains for alcohol and drugs, 5 kilograms (11 pounds) of cocaine was found during searches at Prigozhin’s office in St. Petersburg following the mutiny — an apparent attempt to denigrate the mercenary chief.

After his death, Putin described Prigozhin, 62, as “a man of difficult fate” who had “made serious mistakes in life."

Prigozhin owed his fortune to his ties with the Russian leader dating to the early 1990s and was dubbed “Putin's chef” for the lucrative Kremlin catering contracts.

The Wagner Group military contractor that he created has been active in Ukraine, Syria and several African countries and counted tens of thousands of troops at its peak. It played a key role in the fighting in Ukraine, where it spearheaded capture of the eastern Ukrainian city of Bakhmut in May after months of bloody combat.

In the June 23-24 rebellion, Prigozhin said it was intended to oust the Defense Ministry’s leadership that he blamed for mistakes in pressing the fighting in Ukraine. His mercenaries took over Russia’s southern military headquarters in Rostov-on-Don and then rolled toward Moscow before abruptly halting the mutiny under a deal that offered them amnesty from prosecution. The mercenaries were given a choice to retire from the service, move to Belarus or sign new contracts with the Defense Ministry.

Last week, Putin met with one of Wagner's top commanders to take charge of “volunteer units” fighting in Ukraine in a sign that the Kremlin intends to keep using the mercenaries after Prigozhin's death.

Putin said Thursday that several thousand Wagner troops have signed contracts with the Defense Ministry.