BBC Verify has been tracking the spread of protests across Iran since they erupted in late December, but the near total internet blackout imposed by the authorities has made it extremely difficult to document the scale of the government's violence against those who oppose it.
Despite the blackout entering its third week, a small number of people have managed to get some information out.
Hundreds of close-up images of victims taken from inside the Kahrizak Forensic Medical Centre were leaked to BBC Verify.
We analysed 392 photos of victims and were able to identify 326 people - some had multiple pictures taken of them from different angles. Sources claimed the true number of dead at the mortuary ran into the thousands.
One source, who we are not naming for their safety, told us they weren't prepared for the level of devastation they encountered inside the mortuary complex, and said they saw victims ranging from as young as 12 or 13 to 60 and 70-year-olds. "It was just too much," they said.
Amid the chaos inside the mortuary, family members and friends were huddled together around a screen, we were told. They were trying to identify their loved ones while hundreds of images of the dead flicked across the screen.