Russian activist Ildar Dadin received an official apology on Friday, after being wrongly imprisoned for more than two years.
The letter, which was published on Twitter by Dadin's wife, Anastasia Zotova, bears the signature of the head of Prison Colony No. 5 in Russia's remote Altai region, who apologized "on behalf of the Russian Federation."
The letter also promised that Dadin would be eligible for rehabilitation and compensation for "material and moral harm."
Dadin was the first Russian jailed under controversial anti-protest laws passed in 2014 that target demonstrators who repeatedly commit offenses such as protesting without a permit from local state officials.
The activist was initially imprisoned in Karelia, where he accused prison guards of torturing him and fellow detainees.
The Federal Penitentiary Service claimed that an internal investigation found no proof of Dadin's claims, but nonetheless transferred him to a facility in Russia's eastern Altai region.
The activist was released on Feb. 22, 2017, when Russia's Supreme Court overturned his conviction, upholding the controversial law under which he was convicted but determining that it should only be implemented against “threatening” demonstrators, not “peaceful protesters,” which is how the court described Dadin.