Igor Yakovenko, 52, died in Krasnodar’s SIZO-1 pretrial detention center. The Memorial-backed Political Prisoners Support project considered him a political prisoner.
Yakovenko had been diagnosed with an inoperable brain tumor, Important Stories reported, citing Memorial.
He had been sentenced to five years in prison on charges of preparing to join the Freedom of Russia Legion.
Yakovenko remained in custody after undergoing medical examination.
His classification as a political prisoner is Memorial’s assessment based on the human rights group’s criteria.