Russian opposition activist Sergei Mokhnatkin, who alleged abuse during his years in prison, has died after a long illness at age 66, writer Viktor Shenderovich announced Thursday.

An engineer by profession, Mokhnatkin said he stumbled into activism in 2009 when he attempted to defend a woman being beaten by police during a protest for the right to peaceful assembly which he hadn’t been participating in. He was then twice sentenced for attacking police to jail terms totaling seven years, where he alleged beatings by prison guards.

He soon became a poster child for prison abuse in the eyes of opposition activists, who called his name at the mass anti-Kremlin rallies of late 2011 and early 2012.

He was hospitalized in late 2019, a year after being released from prison, due to complications from injuries sustained in prison, his widow Anna Krechetova told the MBKh Media news website.

“Sergei lost his ability to walk in mid-November 2019 due to multiple spinal fractures,” Krechetova said Thursday. 

She said Mokhnatkin had been refused hospitalization and had developed a life-threatening disease called spondylodiscitis. 

“They’ve been killing him for years and they’ve killed him,” Shenderovich wrote on Facebook.

Krechetova told MBKh Media that a wake in his honor will likely take place after Moscow lifts coronavirus restrictions.