KIEV, Ukraine — Dmytro Groisman, a pioneering Ukrainian rights advocate, has died after years of battling heart disease, his colleague said. He was 41.

Groisman was one of the leading rights defenders in post-Soviet Ukraine, earning widespread respect as a relentless campaigner for justice and crusader against official abuse.

Groisman was one of the founders of the Ukrainian office of Amnesty International and for years campaigned against capital punishment. He then set up the Vinnytsia Human Rights group, which helped refugees and fought against abuse and torture in prisons. His work earned him numerous foes in the government and he was charged with distributing pornography, an accusation he dismissed as absurd and politically motivated.

Fellow activist Maksym Butkevych said Tuesday that Groisman died on Monday of a heart attack after a long illness.