Iranian man dies following 'police torture' on Mashhad street
Mehrdad Sepehri was tied to a metal pole on the street and assaulted by a policeman, using a stun gun and a pepper spray.
The young man died of suffocation and lost consciousness before arriving at the hospital, where marks of beating and suffocation on his neck and wrists were identified by doctors.
The video of the incident on the street sparked anger after it emerged online.
Authorities confirmed an investigation has been launched into the incident, according to the BBC Persian.
It is unclear why the man was being detained by the police officer, but security forces in Iran have been accused of using excessive force against civilians.
In September, Amnesty International accused Iran's security forces of using torture to extract confessions, saying hundreds of people have been jailed since a sweeping crackdown against protests last year.
Amnesty said it had gathered dozens of testimonies from the 7,000 people it estimated were arrested, which included children as young as 10.
The accounts reveal "a catalogue of shocking human rights violations, including arbitrary detention, enforced disappearance, torture and other ill-treatment", the London-based human rights group said.
Those arrested were tortured into "confessions" of involvement in the protests, membership of opposition groups or contact with foreign governments and media, it added.
Torture and other ill-treatment by police, intelligence operatives and others "was widespread", the rights group said.
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Torture techniques included water boarding, beating, electric shocks, pepper spraying genitals, sexual violence, mock executions and pulling out finger and toe nails, Amnesty reported.