Amnesty International urged Iran's judiciary on Wednesday (October 13) to fully investigate the "suspicious" death of inmate Shahin Naseri in custody.
Naseri had testified to witnessing the torture of professional wrestler and protester Navid Afkari, whose execution in September 2020 caused an international outcry.
Naseri, 49, died last month after being transferred from prison in Tehran to an unknown location, according to domestic and expatriate Iranian media outlets.
"Iranian authorities must urgently carry out an effective, thorough, independent, impartial and transparent investigation into the causes and circumstances surrounding the enforced disappearance and suspicious death," Amnesty said.
It added that according to its information, Naseri called at least two individuals from the prison clinic using another prisoner's phone, expressing fears his life was in danger.
"This latest case of enforced disappearance and death in custody serves as yet another stark reminder of the deadly consequences of the crisis of systemic impunity in Iran for violations to the right to life and other crimes under international law," it said.
Amnesty last month issued a report saying that Iran has failed to provide accountability for at least 72 deaths in custody since January 2010, "despite credible reports that they resulted from torture or other ill-treatment or the lethal use of firearms and tear gas by officials".
The Islamic Republic has multiple high-profile corruption prisoners, formerly officials or close to regime officials, who have been sentenced to death years ago, but have yet to be executed.
The regime has a history of rapidly charging political activists accused of "attempting to overthrow the regime" after slapping on the "corruption on earth" charge, a Qur'anic reference used since the 1979 Islamic Revolution for justifying killing political prisoners.
It is similarly used for espionage charges, although not all cases of espionage have resulted in the death penalty.
With regard to the general decision-making process, "the regime does a political cost-benefit analysis", a former Iranian naval analyst who asked to remain anonymous told Al-Mashareq.
Iran's judiciary shows leniency toward domestic activists on the rare occasions it believes the costs are outweighed by the benefits, he said.
Iran's prisons administration has confirmed the death of Naseri, saying he died following an attempt to resuscitate him over an unspecified medical condition.
Amnesty said Naseri had provided "multiple written affidavits" to the authorities in 2019 and 2020 in support of the torture complaints, defence submissions, and appeal and judicial review requests lodged by Afkari.
The 27-year-old wrestler who had won national competitions was hanged in the southern city of Shiraz after being convicted of committing a murder during protests that rocked the city two years before.
But he had complained of being tortured into confessing, with methods that included beating and having alcohol squeezed up his nose.
According to Amnesty, his brothers Vahid and Habib Afkari remain in jail in what it describes as "arbitrary" detention related to the scrutiny over Navid's execution.
Fars province judiciary chief Khazem Mousavi last month denied any relation between Afkari and Naseri's cases and refuted Naseri's testimony.
Meanwhile, Iran has postponed the internationally criticised planned execution of a man arrested for murder when he was 17, but he remains at imminent risk of being hanged, Amnesty and other rights groups said Wednesday.
Arman Abdolali, now 25, was given the verdict after a trial that rights groups described as unfair. His scheduled execution had renewed international criticism of Iran's use of capital punishment.
Abdolali had been moved to solitary confinement in the Rajai-Shahr prison in Karaj, west of Tehran, in preparation for his execution on Wednesday, and held a final meeting with his parents on Tuesday.
But the execution did not go ahead, although there are fears it may take place on Saturday, said Amnesty and the Oslo-based Iran Human Rights (IHR).
The "execution is now postponed to Saturday, 16 October. He remains at risk of imminent execution in Iran. He was just 17 when arrested", Amnesty said on Twitter.
IHR, which monitors the use of the death penalty in Iran, said Abdolali was still being held in solitary confinement, and quoted sources as saying the execution would take place on Saturday.
Amnesty says Abdolali was sentenced to death in December 2015 after being convicted of murder following his girlfriend's disappearance the year before.
But the sentence was handed down in "a grossly unfair trial" by a court that "relied on torture-tainted 'confessions'", it said.
IHR said Abdolali confessed to the murder at the time of his arrest, but the body was never found, and he later withdrew his confessions.
According to rights groups, international conventions signed by Iran prohibit it from executing anyone for a crime committed while aged under 18.
Iran executes more people each year than any nation except China. IHR said at least 64 juvenile offenders have been executed in Iran over the past 10 years, with at least four executed in 2020.
In a sign of international concern over the case, Germany's human rights commissioner Baerbel Kofler said carrying out the execution would be an "unacceptable breach of international law".
"Arman Abdolali was a minor at the time of the alleged crime. There is credible evidence that his confession was obtained under torture and that the conviction thus contradicts fundamental principles of the rule of law," she said in a statement released by the German Federal Foreign Office.