Ion Ficior, who was incarcerated for the deaths of 103 political inmates while in charge of a communist-era labor camp in Romania, has died. He was 90.

Ficior died Wednesday at Jilava prison hospital, according to Bianca Filote, spokeswoman for the government Institute for Investigating the Crimes of Communism. The institute began to pursue Ficior and other former prison guards in 2013 in a bid to make them finally accountable for wrongdoing during the communist era, handing over evidence to prosecutors.

Prison hospital spokeswoman Denisa Ene confirmed to The Associated Press that a prisoner, suffering various chronic medical conditions, had died Wednesday morning, but declined to provide further details, citing privacy rules.

Ficior was serving a 20-year sentence there for crimes against humanity. He was imprisoned in March 2017, but denied wrongdoing and said he was merely following orders.

But Andrei Muraru, who initiated the investigation of Ficior, said he "showed a complete lack of mercy toward his victims, who endured prolonged suffering, were skeletal inmates, or defenseless elderly people," he told the AP.

"They were subjected to a diabolic program of extermination through exhausting work, hunger and physical torture," said Muraru, now an adviser to President Klaus Iohannis.

Ficior was commander at the Periprava labor camp from 1958 to 1963. During his trial, former detainees accused him of beatings, a lack of food and medicine, overwork and unheated cells.

In an interview with the AP in 2013 before he was charged with more than 100 deaths, Ficior claimed "two or three had died" while he was prison commander.

Romania had about 500,000 political prisoners under the Communist regime, about one-fifth of whom died while in detention, according to historians. Many were locked up for merely falling afoul of the communist regime. A general amnesty was granted to political prisoners in 1964.

Ficior is survived by a son.