Sergei Mamaev
Sergei Mamaev, born 1980, Mari El. Charges: Article 282.2 (part unknown), Russian Criminal Code (Organizing the activities of an extremist organization); “Sergei Mamaev's case of involvement in the activities of an extremist organisation”. Sentence (February 16, 2026): 2 years 8 months' imprisonment in a general regime colony. Status: imprisoned; deprived of liberty since July 22, 2025. Recognition: Memorial: Support for Political Prisoners — recognised as a political prisoner, September 11, 2025.
In brief
Mari El · Yoshkar-Ola · Construction workers · Extremism cases, Cases against Navalny/ACF supporters
Sentence
2 years 8 months
imprisonment in a general regime colony
Upheld April 29, 2026
Charges
- Article 282.2 (part unknown), Russian Criminal Code — Organizing the activities of an extremist organization
Full wording of the charges
According to journalist Alexei Seregin, Mamaev is accused of six incidents dated between 2023 and 2025. The exact reason for the prosecution is not yet known. "Some of these dates coincide with Alexei Navalny's death, his funeral, and the anniversary of his death. On Vkontakte, Mamaev posted short notes and photos of himself laying flowers at the memorial for victims of political repression in Yoshkar-Ola," the journalist wrote. One of the cited dates is 4 June 2023. That day, Sergei Mamaev posted a selfie wearing a T-shirt reading "Free Navalny" on the politician's birthday. He was fined 1,000 rubles (US$13) for the photo. On 3 and 20 August the same year, Mamaev shared links to videos on Alexei Navalny's channel, according to "7×7" media outlet. On 17 March 2024, he posted a photo of a ballot with "Navalny" written on it during the "Noon Against Putin" event, promoted by the founder of "FBK". On 26 March 2024, Mamaev posted a photo of Navalny on the 40th day after his death. On 4 June 2025, he again laid flowers in memory of Navalny on his birthday.
Latest event
May 21, 2026 — added to the rosfinmonitoring list of “terrorists and extremists”
Recognition by rights defenders
- Recognised as a political prisoner — Memorial: Support for Political Prisoners, September 11, 2025
Timeline
· Added to the Rosfinmonitoring list of “terrorists and extremists”
· Appeal ruling
upheld
· First-instance verdict
guilty verdict · 2 years 8 months
· Recognised as a political prisoner
Memorial: Support for Political Prisoners
· Preventive measure: pre-trial detention
Pre-trial Detention Centre №1 (SIZO-1) of the Federal Penitentiary Service of Russian Federation for the Republic of Mari El
· Preventive measure: placement in a temporary detention facility
· Persecution begins
Sergei Mamaev's case of involvement in the activities of an extremist organisation
Criminal case
Sergei Mamaev's case of involvement in the activities of an extremist organisation
- Case number
- 1-60/2026 (1-770/2025;)
Write a letter
The address is not listed in the database.
Details and sources
Full summary
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.
All fields of the record
- Citizenship
- Russia
Other people prosecuted under Article 282.2 (part unknown), Russian Criminal Code
Under the same article, not necessarily in the same case.