Sergei Mamaev
Yoshkar-Ola
46 yr old (born in 11.03.1980)
Address: 424000, Россия, респ. Марий Эл, г. Йошкар-Ола, ул. Советская, д. 100, ФКУ СИЗО-1 УФСИН России по Республике Марий Эл, Мамаев Сергей Олегович, 1980 г.р.
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An activist from Yoshkar‑Ola, a city east of Moscow in central Russia. On 22 July 2025, he reported that he had been detained in a case concerning an "extremist organisation" linked to the activities of Alexei Navalny’s regional offices. The following day, he was remanded in custody.
The prosecution appears to have been based on social media posts and participation in events dedicated to Navalny. On 16 February 2026, Mamaev was sentenced to two years and eight months in a general-regime penal colony.
You can read more about politically persecuted people in the Telegram channel OVD-Info LIVE and our database of politically motivated criminal prosecutions.
Sergei Mamaev
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Address: 424000, Россия, респ. Марий Эл, г. Йошкар-Ола, ул. Советская, д. 100, ФКУ СИЗО-1 УФСИН России по Республике Марий Эл, Мамаев Сергей Олегович, 1980 г.р.
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