Pyotr Versilov said he last knew the whereabouts of his wife, Nadezhda Tolokonnikova, Oct. 21 when guards put her on a train to a different prison, the BBC reported Saturday.
She had been on a hunger strike at a penal colony in Mordovia in western Russia.
A fellow passenger reported seeing her on the train three days later when the train arrived in Chelyabinsk, in the Ural mountains.
Tolokonnikova and another band member were sentenced to two years in prison after performing a crude protest song at a Moscow cathedral in February 2012. A third members was released on appeal.
Versilov told the U.S. website BuzzFeed he believed authorities in Moscow ordered her transfer because "they wanted to cut her off from the outside world."
He said his wife was still weak after two hunger strikes.
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