Kouchner told POLITICO, “It’s a crime against humanity and must be taken into account by the International Criminal Court.  The entire international community has a responsibility to shed light on these events and ensure that the criminals behind them face an investigation.”

Last month a recording surfaced that revealed disagreements among Iranian officials in the summer of 1988.  Hossein Ali Montazeri, who was to become Khomeini’s successor, can be heard arguing with an audience made up of a sharia judge and prosecutors, saying that the mass killings were “the biggest crime in the Islamic Republic, for which history will condemn us.”  A member of the audience asked if he could carry out a final set of 200 executions, to which Montazeri responds that he would not authorize a single one.

A fatwa had been issued by Ayatollah Ruhollah Khomeini, ordering the execution of all political prisoners, who were already locked up in Iranian jails. The members of an opposition group named Mujahedin-e Khalq (MEK), seemed to be targeted.  Khomeini called them “hypocrites”.

Thousands of prisoners were condemned to death by ad hoc tribunals over the course of a just a few months. Amnesty International estimates that around 4,500 people across the country were killed during the massacre.  Opposition groups allege that the death toll was closer to 30,000, with victims including teenagers as young as 14 and pregnant women.

“This is a crime against humanity of great magnitude,” said William Bourdon, a French lawyer for Transparency International who has handled human rights cases, notably representing Franco-Chilean families in a case against General Augusto Pinochet. “The International Criminal Court has prosecuted crimes that were of smaller magnitude, but there is no doubt this would fit their definition.”

Montazeri paid for following his conscience.  He was placed under house arrest until his death in 2009. His son, Ahmad, published the recording on August 9, on a website dedicated to Montazeri’s memory.

MEK officials presented allegations that members of the “death councils” are now among the top members of President Hassan Rouhani’s administration, at a news conference this week.  For instance, Mostafa Pour-Mohammadi, is now Iran’s justice minister, and  Hossein-Ali Nayyeri, is the current head of the Supreme Disciplinary Court for Judges.  Both were active members of the “Death Committee”.

“We call on the international community to shed light on these events, though we do not underestimate the obstacles,” said Bourdon. “There are tools that can help us end this insolent impunity.”  

He points out that an international investigation into the killings would require that one or more governments raise the issue at the United Nations.  However, the recent preliminary business deals being discussed between Iran and Western countries has governments reluctant to jeopardize economic interests.

“There is nothing impossible about making an ad hoc tribunal to address this case,” Bourdon said. “The question needs to be taken up by governments.”