Alex Wong via Getty Images Vladimir Kara-Murza, 35, left, had been active and healthy recently, his wife said.

Vladimir Kara-Murza, a fierce critic of Russian President Vladimir Putin, has been hospitalized for organ failure two years after he nearly died of a suspected poisoning, his family confirmed to several media outlets.

Kara-Murza, a 35-year-old journalist working for Open Russia, the pro-democracy group founded by now-exiled Russian businessman Mikhail Khodorkovsky, has been on life support and in a medically induced coma since falling ill on Thursday, his wife, Evgenia Kara-Murza, told the BBC.

“It’s the same clinical picture,” she said, referring to the kidney failure he suffered in 2015. Medical tests at the time found that the illness was caused by poisoning, though it was never determined whether it was intentional or accidental.

“The reason is unclear, like last time,” she said, noting that his symptoms are also the same. “He’s been active and healthy [recently].”

His father told Russian daily newspaper Moskovsky Komsomolets that doctors did not suspect a second poisoning, The Guardian reported.

“It’s just that the poisoning two years ago didn’t pass without a trace,” his father said. “My son’s health is weakened.”

U.S. officials noted that the mysterious illness was disturbing given Putin’s history of censoring his critics.

Sen. Tim Kaine (D-Va.) tweeted that Kara-Murza’s condition was “troubling news.”

Troubling news given Putin's history of silencing opposition, and Vladimir Kara-Murza's previous poisoning https://t.co/IMrWEw7n9W — Senator Tim Kaine (@timkaine) February 2, 2017

“Vladimir Putin does not deserve any benefit of the doubt here, given how commonplace political assassinations and poisonings have become under his regime,” Sen. Marco Rubio (R-Fla.) said in a statement. “I am praying that Kara-Murza’s condition improves, and I urge the Trump Administration, including Secretary of State Tillerson, to make Kara-Murza’s cause America’s cause, question Russian authorities about this, and ultimately hold Putin accountable if he was targeted by the regime.”

Earlier on the day he was hospitalized, Kara-Murza posted a photo to Facebook memorializing his friend Boris Nemtsov, another Putin critic and former Russian statesman who was shot dead in February 2015, just steps from the Kremlin in one of the safest areas of Moscow.

His death is one of several such killings that have occurred under Putin’s reign. While Russian investigators implicated several Chechens in the assassination, Nemtsov’s political allies suspected a cover-up.