Ebrahim Raisi, the favorite in Iran's presidential election, has used his position at the heart of the judiciary for grave rights violations, including mass executions of political prisoners, activists say.
They say Raisi -- who now has victory in his sights on Friday after even conservative rivals were disqualified in vetting -- should face international justice rather than lead his country.
“Raisi’s only place is in the dock, not the presidency,” said Justice for Iran Executive Director Shadi Sadr.
“The mere fact he is currently the head of judiciary and running for president demonstrates the level of impunity that the perpetrators of the heinous crimes enjoy in the Islamic Republic of Iran,” she said.
The 1988 killings, which took place from July to September that year allegedly on the direct orders of revolutionary leader Ruhollah Khomeini, remain a near taboo in modern Iran.
Most rights groups and historians say between 4,000 and 5,000 were killed, but the political wing of the MEK, the National Council of Resistance of Iran (NCRI), puts the figure at closer to 30,000.
Last year, seven special UN rapporteurs told the Iranian government that “the situation may amount to crimes against humanity” and urged an international probe if Tehran did not show full accountability.
Amnesty International came to a similar conclusion in a 2018 report, which identified Raisi as a member of the Tehran “death commission” that secretly sent thousands to their deaths in Evin prison in Tehran and Gohardasht prison in Karaj.
The vast majority of the bodies were buried in unmarked mass graves and Iran continues to conceal the fate of the victims and the whereabouts of their remains, it charged.
The rights group’s Iran researcher Raha Bahreini told AFP that Raisi should be “criminally investigated for the crimes against humanity of murder, enforced disappearance and torture”, including by foreign countries under the principle of universal jurisdiction.