Sergei served in military unit 7404 in Baranovichi, where he rose through the ranks from company commander to unit commander. In 2013, he became deputy head of the Department of Corrections, responsible for ideology and personnel. He also conducted prison tours for state media and interacted with the Belarusian Orthodox Church. At the turn of 2018, he resigned from his post and, in January 2019, registered in Minsk as a sole proprietor in the daily rental sector.
Sergei and his wife were found guilty in August 2024 in a criminal case brought under the article "organizing and preparing actions that grossly violate public order, or active participation in them" and sentenced to imprisonment in a penal colony.
On November 28, 2024, another court hearing was held on the criminal case brought under the article "organization and preparation of actions that grossly violate public order, or active participation in them." Following this hearing, Sergei was also sentenced to imprisonment in a penal colony.
According to human rights activists, he was released in the winter of 2026, having fully served his sentence imposed by the court.
