Sergei was convicted of participating in "mass riots" in a criminal case opened due to protests and clashes between Pinsk residents and security forces on the night of August 9-10, 2020. The victims in the case included 109 police officers and officials, who, in addition to prison sentences for the accused, demanded approximately 530,000 rubles in compensation.
In November 2024, Sergei's sentence was increased and he was transferred to prison.
On March 19, 2026, he was released after another visit to Minsk by US President Donald Trump's special representative, John Cole, and taken to Lithuania.
