Photos captured by a Syrian military police officer known by the alias "Caesar" documenting torture and deaths in detention centers are poised to become critical evidence in legal proceedings against Bashar al-Assad's regime.

The Caesar files, which consist of tens of thousands of images, expose systematic human rights violations.

The images are expected to gain prominence as transitional justice mechanisms are implemented in the event of political changes in Syria.

A regime of repression

Stephen J. Rapp, who served from 2009 to 2015 as US ambassador-at-large for war crimes issues, heading the Office of Global Criminal Justice in the State Department, characterized the Assad regime as one that "survived by terrorizing its own people."

"The regime responded to peaceful protests that were hoping to democratize Syria with the most repressive campaign you could imagine," Rapp said. "Sort of on the book of Stalin or the Nazis, basically going after everyone that they thought could be a risk to the regime."

Rapp said that after the civil war erupted in 2011, hundreds of thousands of people were targeted by the regime. Many peaceful protesters were detained, tortured and killed in facilities notorious for their brutality.

He also pointed out the regime's use of chemical weapons against civilians, which constitutes a violation of international law.

Despite pledging under international pressure to eliminate its chemical weapons stockpile, the Assad regime continued deploying toxic agents such as chlorine and sarin gas in its attacks.

"We have to prevent these crimes from happening in the future. The best way to do that is to hold accountable those that were responsible," Rapp emphasized.

Caesar’s role in exposing atrocities

Caesar, a former regime soldier, was tasked with photographing the corpses of detainees who died in custody.

From May 2011 to August 2013, he captured thousands of images showing evidence of torture, starvation and other inhumane treatment.

"He (Caesar) is not a political kind of individual. He was a military policeman, as you see from all the photos that he brought out," Rapp said.

"He was deeply involved in military investigations of assassinations and other things, and you see photos of events, even among his sort of second collection of photos that he made from before the uprising."

Each corpse was assigned a number corresponding to its detention center, but no effort was made to record the victims' identities.

The images reveal harrowing evidence of systematic torture, including gouged eyes, crushed skulls and signs of starvation and disease.

Caesar eventually fled Syria, smuggling approximately 55,000 photographs – critical evidence of the regime’s practices.

"He faked his own death, managed to be smuggled out of the country, and eventually got to Doha, where he met with the team of my colleagues who really have been able to analyze some of it," Rapp recounted.

Global response to Caesar files

Although Caesar found refuge in a European country, Rapp criticized the lack of international response to the photos.

"We brought out the evidence of men, women and children tortured to death by their own government, and the world didn't react," he said.

Efforts to prosecute Syrian officials have faced challenges, including vetoes by Russia and China at the UN Security Council.

Nevertheless, institutions in the US and Europe have authenticated the photographs, which have since been used as evidence in international trials.

Rapp expressed optimism about future accountability.

"History shows that opportunities to hold perpetrators accountable often emerge when regimes lose power or face significant international pressure," he said.

He underscored the necessity of transparent and inclusive judicial processes to address these crimes.

Rapp also emphasized the role of transitional justice mechanisms such as truth commissions and investigations into the fate of missing persons as vital steps toward accountability and reconciliation.