A 27-year-old man who is one of six people sentenced to death in Iran over ongoing anti-regime protests has been subjected to several mock executions in prison, the BBC reported

Last month, a Revolutionary Court found Sahand Noormohammadzadeh guilty of acts of “vandalism and arson of public property with the aim of causing disruption to the country’s peace and order and confronting the Islamic government,” according to the Mizan News Agency.

Prosecutors accused him of taking part in riots by blocking a highway and setting fire to bins and tires. They showed the court a video in which a man in a mask, whom they claimed was the defendant, is seen pushing a burning garbage can onto the road and placing a railing between two lanes.

Noormohammadzadeh protested his innocence and his lawyer told the court there was no evidence to suggest that his client was the masked man.

A source told BBC Persian that interrogators falsely informed Noormohammadzadeh that his mother had suffered a heart attack and that he must sign a letter if he wanted to speak to her before she died. The letter, according to a lawyer in Tehran, amounted to an admission of guilt, the BBC reported.

The court sentenced Noormohammadzadeh to death for “enmity against God” and he has been subjected to mock executions three times in prison, a source told BBC Persian.

A mock execution is a form of psychological torture whereby a victim is made to feel that their execution is taking place but is not carried out. The BBC’s source said that even before his trial, Noormohammadzadeh was told “to go on a chair, blindfolded, to be hanged.”

Amnesty International has warned that at least 21 people are at risk of being sentenced to death in “sham trials” over the protests in Iran.

While the sentences of the six defendants handed a death penalty can be appealed, judiciary chief Gholamhossein Mohseni Ejei said on Monday that the executions would take place soon, the BBC reported.

About 18,200 people are estimated to have been arrested since the nationwide protests erupted in September in response to the death in police custody of Mahsa Amini, according to the Human Rights Activists News Agency. Many of them reportedly have been tortured or subjected to other forms of ill-treatment while in custody.