Warning: The following story contains graphic details of violence which some readers might find upsetting.
A BBC Persian analysis of hundreds of videos and photographs taken during recent protests in Iran confirms the security forces' use of a wide range of weaponry, including machine guns, snipier rifles and shotguns.
Protesters were reportedly killed in many of the more than 200 cities where protests had been recorded. While the exact death toll remains unclear, the level of brutality and the deployment of lethal weaponry evidenced in pictures, witness accounts and reports by human rights groups and the media show thousands have been killed across the country.
The crackdown on protests - which began over the economy but rapidly escalated - employed a level of violence unprecedented in modern Iranian history.
"This is the largest mass killing in contemporary Iranian history and one of the largest in the world," Payam Akhavan, an Iranian Canadian former UN prosecutor at the International Criminal Court, in The Hague, told BBC News Persian.
