Wife of Vladimir Putin critic Vladimir Kara-Murza says her husband was poisoned

Russian opposition activist Vladimir Kara-Murza is on life support in Moscow for organ failure, and his wife has spoken out to say she believes he was poisoned.

In an interview with BBC's Sarah Rainsford, Evgenia Kara-Murza described her husband's symptoms of an accelerated heart rate and trouble breathing, before his organs began to fail at the hospital.

Kara-Murza is part of the Open Russia foundation, an organization of anti-Putin activists who call for open elections, civil rights reforms and a free press.

SEE ALSO: Putin signs new law decriminalizing some forms of domestic violence

Kara-Murza's friend Boris Nemtsov was killed beside the Kremlin two years ago, but Kara-Murza carried on in his stead.

While the hospital will not comment publicly on his condition, Evgenia says their official diagnosis is an acute intoxication by an unidentified substance -- something she later put bluntly as "poisoning."

RELATED: The uncertain future of 2017

"This is poisoning," Evgenia wife said. "There are no other options left."

Evgenia says she has sent DNA samples to Israel and France for further toxicology testing.

"Anything can happen to people who choose to stand up to Putin," she said. "We are hoping to find some answers."

Sen. John McCain spoke in favor of Vladimir Kara-Murza on the Senate floor on Tuesday, as he slammed President Trump for defending Vladimir Putin over the weekend when he said he "respects" him and normalized the concept of nation state leaders as "killers."

SEE ALSO: Syria's Assad sees Trump's Islamic State view as promising

"We got a lot of killers," Trump said. "What, you think our country is so innocent?"

Kara-Murza "knew that there was no moral equivalence between the United States and Putin's Russia. I repeat, there is no moral equivalence between that butcher and thug and KGB colonel and the United States of America, the country that Ronald Reagan used to call a shining city on a hill," McCain said. "To allege some kind of moral equivalence between the two is either terribly misinformed or incredibly biased. Neither, neither can be accurate in anyway."

Sen. Marco Rubio has also expressed concerned over Kara-Murza's illness, and believes Putin should be held accountable if any evidence is discovered of foul play.

"Vladimir Putin does not deserve any benefit of the doubt here, given how commonplace political assassinations and poisonings have become under his regime," said Rubio. "I am praying that Kara-Murza's condition improves."

RELATED: Vladimir Putin throughout the years