Vladimir Kara-Murza says he was poisoned twice for speaking out against the policies of Russian President Vladimir Putin. Despite being at death’s door in both incidents, the political activist tells Lesley Stahl he will return to Russia to continue his protests. Kara-Murza appears on the next edition of 60 Minutes Sunday, March 12 at 7 p.m. ET/PT.

“Of course, I will absolutely go back to Russia,” he says in the interview conducted in a suburb of Washington, D.C. where his family lives. “I am Russian, this is my country, and I believe in what I do, in what my colleagues do. There are many of us.”

Vladimir Kara-Murza CBS News

Kara-Murza is just one of several Kremlin critics who have been the victims of unsolved shootings, questionable suicides, and poisonings. “Many, unfortunately, have died. I’m the fortunate one. I’m still here, I’m still talking to you. Many of my colleagues cannot do that,” he tells Stahl.

“Many, unfortunately, have died. I’m the fortunate one. I’m still here, I’m still talking to you. Many of my colleagues cannot do that.”

In the first incident in May 2015, he says his doctors told his wife he had only a five percent chance of living. It took him almost a year to recover. In the second illness, he says he was luckier because the doctors had seen his symptoms before and immediately knew how to treat him. Last month, he was flown back to the U.S. He’s recovering faster but still retains a slight limp.

Sources in line with the Kremlin have told 60 Minutes that Kara-Murza’s story may be concocted by the opposition to tarnish Putin and his administration.

Kara-Murza, who spent a month in the Russian hospital last time and over two weeks this time, is being monitored by doctors since his arrival to the U.S. He tells Stahl, “To those who say that this is a plot, I honestly, and I mean this sincerely, I wish they never have to experience what I’ve experienced twice in the last two years, when you’re trying to breathe and you cannot. When you feel your organs shutting down, giving up on you one after another. And when you feel the life coming out of your body in the next few hours, and you don’t remember anything for the next month. And then for the next year you’re trying to relearn how to walk, how to use cutlery, you know, how to talk to your kids again. I-- I wish these people who tell you these things never have to experience this. I honestly, sincerely do.”