The case also promises to offer a rare insight into atrocities allegedly committed by the Iranian state during one the darkest periods in its modern history — summer 1988 — when reports by human rights organizations say thousands of members of political opposition groups were executed on the orders of supreme leader Ruhollah Khomeini.

The case is particularly sensitive for Iran now because its new president, Ebrahim Raisi, has long stood accused of being a central figure in the massacre, as a member of a committee that ruled who should be killed and who should be spared during the purge.

International organizations have long pressed Iran to address this murky chapter in its past, something Tehran has resisted.

But now, an international legal principle known as universal jurisdiction — which permits one state to try cases of serious alleged criminality in another — has given Sweden an opportunity to take its own look.

In 2019, Swedish police arrested Noury as he landed in Stockholm for a family visit.

Since then, Mesdaghi and other witnesses have come forward to say Noury — then known by the name Hamid Abassi — worked as an assistant prosecutor at Gohardasht overseeing beatings and executions.

“I witnessed what happened,” Mesdaghi said. “I was blindfolded, but I could see from behind the blindfold.”