Just days ahead of a peace conference that is supposed to guide how the West will proceed with a plan for peace in Syria, a new report alleges that President Bashar al-Assad tortured and killed thousands of detainees over two years 

The Guardian and CNN shared the exclusive on the 31-page report written by celebrated international lawyers that allegedly shows the "systematic killing" and torturing of about 11,000 detainees carried out by the Assad regime in Syria between March 2011 and August 2013. The report can be read here, and drew its conclusions from interviews with defectors and evidence provided by a former military police photographer.

"Caesar," allegedly a former photographer for Syria's military police, leaked over 25,000 photos showing numerous detainees allegedly killed by the Syrian regime and answered questions about his work for the team of experienced war crimes lawyers who compiled the report. He said his job was "taking pictures of killed detainees." He smuggled the photos out of Syria with help from his brother, who had contact in the Syrian National Movement. Caesar and his family eventually fled the country for his own protection with help from the team behind the report. 

The lawyers who authored the report have a long history prosecuting war criminals: Professor Sir Geoffrey Nice, the former lead prosecutor against former Yugoslav President Slobodan Milosevic; Sir Desmond de Silva, a former chief prosecutor of the Special Court for Sierra Leone; David Crane, the first chief prosecutor of the Special Court for Sierra Leone who indicted former Liberian President Charles Taylor. The three men were hired by British law firm Carter-Ruck to author the report. Carter-Ruck was financed by the government of Qatar. They subjected the evidence to rigorous scrutiny by showing everything to "a forensic pathologist, an anthropologist and an expert in digital imaging," to verify the images as best as they possibly could.

Some of the bodies show signs they were strangled, electrocuted or brutally beaten. Many of the bodies were frail and thin in a way that can only be brought on by prolonged starvation. Evidence and testimony provided by Caesar also describes a ruthless bureaucratic system used by Assad to document and cover-up every killed detainee. Per the Guardian

The reason for photographing executed persons was twofold. First to permit a death certificate to be produced without families requiring to see the body, thereby avoiding the authorities having to give a truthful account of their deaths; second to confirm that orders to execute individuals had been carried out."

Families were told that the cause of death was either a "heart attack" or "breathing problems", it added.

"This is a smoking gun," Crane told CNN. "Any prosecutor would like this kind of evidence — the photos and the process. This is direct evidence of the regime's killing machine." Another author compared the pictures included in the report to images of Nazi death camps from World War II.