The British newspaper Guardian on Thursday has published an investigation with footage showing a massacre taking place in Tadamon, a suburb south of Syrian capital Damascus, under the Bashar Assad regime in April 2013.

The piece was called "Massacre in Tadamon: how two academics hunted down a Syrian war criminal," and written by Middle East correspondent Martin Chulov.

It was there that groups of civilians were rounded up, sent towards an execution pit, and shot dead.

The British newspaper reported that the mass grave contained at least 41 bodies following the massacre. The bodies were then doused with fuel and set alight. In the video footage, soldiers could be heard laughing.

The massacre was carried out by Branch 227 of Syria’s military intelligence, the Guardian reported. It took place just a few miles from Syrian regime leader Bashar Assad’s seat of power.

Chulov said the footage is "one of the most indictable videos from the whole Syrian conflict" and "gives us a glimpse into a previously untold part of the 10-year war."

The footage was recorded by a new recruit to a loyalist militia, who leaked it first to an opposition activist in France and then to two researchers: Annsar Shahhoud and Prof. Uğur Ümit Üngör of the University of Amsterdam’s Holocaust and Genocide Center.

Annsar, a critic of the Assad regime, created an alias on Facebook in order to reach out to regime officials.

In March 2021, she connected with a man called Amgd Youssuf, who is alleged to be one of the gunmen in the video.

The two researchers passed on their evidence, comprised of videos, notes and thousands of hours of interviews, to prosecutors in the Netherlands, Germany and France. The source is safe outside Syria.