Amnesty International - 'For nearly three decades, the Iranian authorities have systematically concealed the whereabouts of the remains of thousands of prisoners of conscience and others detained on politically motivated charges who were forcibly disappeared and extrajudicially executed by the Iranian authorities between late July and early September 1988. Based on information provided by family members of victims, human rights defenders, Persian-language media outlets and political opposition groups, Justice for Iran estimates that there may be more than 120 locations across Iran that contain the remains of these victims. Many grave sites are located in deserted areas inside or in the vicinity of cemeteries'.

A full report by Amnesty International can be found in the link below:

Rouhani Executions
Under Rouhani
Imprisonment and Execution of Christian leaders