Despite efforts by medical staff, Rouhi could not be saved, Mizan added.
Nowshahr Prison Public Relations has initiated an investigation into the incident while the officials say prison’s closed-circuit cameras will be reviewed.
The body has been sent for forensic examination to determine the cause of death and conduct toxicological tests.
An autopsy and sampling have already been performed.
Rouhi, who had been sentenced to death three times by the initial court, openly admitted his role in last year’s unrest and deadly riots in Nowshahr and described his actions leading up to the deadly incidents in northern Iranian city.
During the riots, Rouhi also confessed to receiving a copy of the Holy Quran from a woman present at the scene and subsequently throwing it into the fire, burning it.
He also admitted to participating in setting fire to the traffic police headquarters located in the city center. As confessed by Rouhi, he and a few others had entered the building and threw down items before igniting it.
