Financier Bill Browder says Putin is likely at the root of a string of Russian executive deaths.
Calling them an "epidemic of murder," he likened Putin to a mafia boss extorting top businessmen.
Putin could be pressuring them for cash to help finance his assault on Ukraine, Browder said.
Financier Bill Browder said President Vladimir Putin is likely behind an "epidemic of murder" of numerous high-level Russian executives.
Browder, who until 2005 was Russia's biggest foreign investor, is one of Putin's most high-profile critics. A string of unexplained deaths of more than a dozen top Russian business figures is likely connected to Putin acting as the country's "mafia boss," Browder said.
He made the comments on a podcast released by Australian network ABC News on Sunday.
In 2022 alone, at least 15 executives - most with strong ties to Russia's energy industries - have died in unusual ways. Authorities in Russia have generally called them accidents or likely suicides.
Browder outlined the various reported causes of death, which have included dramatic falls, drownings, and murder-suicides.
"Generally in Russia if somebody dies in that way, one should view it as suspicious," he said.
"And when people all of the same industry die that way, it looks to me like what I would call an epidemic of murder.
"You should rule in the foul play, not rule it out."
String of deaths
These deaths include the apparent murder-suicide of Novatek executive Sergey Protosenya and most of his immediate family in Catalonia, in April. It is still under investigation by Spanish authorities, local force Mossos D'Esquadra confirmed.
The body of Putin's point man at Russia's Far East Development Corporation, Ivan Pechorin, also washed up on the shore around 62 miles from Vladivostok in September after he reportedly fell from a speeding boat, per local media.
One executive, 67-year-old Ravil Maganov, was chair of the board of directors at major energy company Lukoil, was reported by state-controlled media as having fallen out of a hospital window in an apparent suicide. Six months earlier, Lukoil's board had been critical of Putin's war in Ukraine.
But Browder said he didn't think Maganov's death was likely to be retribution for his criticism.
He said the deaths were more likely to have happened due to the cost of waging war in Ukraine.
"What I see is that because of the war, there's a lot less money, and when here's a lot less money, whatever money is around becomes a lot more coveted," he said. "These people all sit in front of large cashflows or assets."
Shadowy figures have likely requested that this "unbelievably lucrative flow of cash" is redirected, he said. And when the executives say no, "the best way of getting that flow of cash is to kill him and then ask his replacement the same question."
Asked what role Putin has in this, Browder said that Putin would be getting a cut: "My own experience says that Vladimir Putin is the mafia boss. He is the head of state, but he is also the mafia boss."
Little is known for certain about Putin's vast wealth, but multiple independent investigations have suggested it is strongly interconnected to his network of oligarchs and their business holdings in a highly opaque way.
And that potential source of funding has been "kneecapped" by the West's extensive sanctioning of oligarchs, Browder said.
"The only money that hasn't really been sanctioned has been the revenues from the oil and gas industry, and he needs more money now to run his war," he said.
Browder is the co-founder of successful fund Hermitage Capital, which invested heavily in Russia until his efforts to expose corruption there ended in his expulsion from the country.
After his expulsion his lawyer, Sergei Maginitsky, was imprisoned and died there. Browder lobbied Congress to pass an act in Maginitsky's name to punish Russian human rights violations.