Iran's Prison Organization confirmed the death of two detainees in jail south of Tehran and opened an investigation into the circumstances.
The Prison Organization formed a committee to investigate the death of Amir Hossein Hatami, 22, in Greater Tehran Prison, announced the authorities in a brief statement, AFP reported.
The Kurdistan Human Rights website, which monitors violations against Kurds in Iran, reported that the detainee made a phone call before his death and pleaded for help from his father.
On Sunday, Iran's Ghanoun newspaper reported that Hatami was arrested after getting into a fight without providing additional details.
Hatami's father said that his son was "beaten by prison officers," and his family learned in the call that he was waiting to be taken to the hospital, according to people close to the victim.
They indicated that he had difficulty speaking before his family received a call from the prison the following day, informing them of his death.
Videos circulated on social media of a protest in front of the Great Tehran Penitentiary, also known as Fashafouyeh prison.
Previously, head of the Prison Organization, Mohammad-Mehdi Hadj-Mohammadi had announced the death of Shahin Naseri in custody, asserting that a committee would investigate the incident.
Naseri testified in the 2020 murder trial of wrestler Navid Afkari, who was executed last year.
The two incidents sparked outcry on social media, prompting authorities to issue a statement.
Hadj-Mohammadi said in a statement published by the judicial authority's website, Mizan Online, that he is waiting for the final report of the investigation.
Last August, Hadj-Mohammadi blamed prison officials for "unacceptable behavior" after foreign media outlets published footage from the notorious Evin Prison, north of the capital, showing detainees being beaten and mistreated.
Amnesty International leaked surveillance footage from Evin, showed "appalling abuse of prisoners," which is evidence of the torture and other cruel, inhumane and degrading treatment prisoners receive.
Iran criticizes reports issued periodically by the United Nations and human rights organizations accusing Tehran of mismanaging prisons and mistreating detainees.
Amnesty denounced the impunity granted to prison officials in Iran. At least 70 deaths in custody in ten years have been confirmed, with information indicating that many of these deaths are linked to torture.
On September 8, Yaser Mangouri, 31, was reported dead in Urmieh, in the West Azerbaijan province, by the Ministry of Intelligence.
Amnesty investigated the cases of 72 men and women who were recorded as having died in custody since January 2010 in Iran. The deaths occurred at 42 prisons and detention centers in 16 provinces across the country.
In 46 cases, informed sources, including the deceased's relatives and/or fellow inmates, reported that the death resulted from physical torture or other ill-treatment at the hands of intelligence and security agents or prison officials.
In July, Amnesty International and other NGOs urged the United Nations Human Rights Council members to establish an investigative mechanism to collect and analyze evidence of the most serious crimes committed in Iran.