They are brutal images, showing signs of torture, starvation and in some cases what appears to be outright execution — and they were taken inside hospitals controlled by Syria's military.

The photos — numbering more than 55,000 — were taken by a team of military forensic photographers and smuggled out of the country in 2013 by one of the team's members, a man code-named Caesar.

"I wanted to show the international community the slaughter, the ongoing … massacres that are occurring in Syria," Caesar said in an exclusive interview with CBC's The Fifth Estate as part of a joint investigation with Radio-Canada's Enquête.

Watch The Fifth Estate: The Truth Smugglers, Friday at 9 p.m. on CBC Television

The photos have been authenticated by the FBI. Human Rights Watch estimates they show evidence of at least 6,000 Syrians who died in Syrian regime custody.

Today, they are being used by international war crimes investigators attempting to build criminal cases against the regime of President Bashar al-Assad.

In his first face-to-face television interview, Caesar told The Fifth Estate about what he witnessed while working in military hospitals.

"Look at this picture, for example," he says, showing a photo of bodies scattered on a floor — some emaciated and some with blood and visible trauma on their faces.

"Even animals, it's not OK to treat animals the way these people are being treated."

Prior to 2011 and the start of popular anti-Assad uprisings, the military forensic unit photographed crime scenes for the Department of Defence.

Demonstrators protesting against Syrian President Bashar al-Assad gather in Hula, near Homs, on Nov. 13, 2011. (Reuters)

But then came the government crackdown and tens of thousands of protesters were detained. It was shortly after that, Caesar says, that bodies started showing up in military hospital morgues showing evidence of torture.

For the 'higher command'

Caesar said his job then became to document the deaths for soldiers and officers wanting to prove they'd carried out instructions.

"The officers in the regime, soldiers, et cetera, needed to prove to their higher command that they were actually fulfiling the orders of killing and torturing civilians in these horrific ways … just to show their superiors that they were doing what they were told to do," he says.

"[It]'s important to remember that they don't see a consequence for actions that they do, so even in documenting these things they believe that they are above international law."

In the six years since the civil war began in Syria, an estimated 500,000 Syrians have been killed. Five million have been forced to flee and more than 100,0000 are missing, believed to have been detained by government intelligence and security forces.

According to human rights groups, many were arrested for protesting. Among the missing are teens and children.

This photo is one of thousands that the photographer known as Caesar smuggled out of Syria in 2013, depicting scenes of torture, starvation and death. (Caesar collection)

"What did this child do? He is barely 15 or 16 years old at most," Caesar says as he shows a photo of a young person's body on the ground, emaciated.

"What does he know about politics? If anything, he may have joined a single protest where they were calling for equal rights ... but this child, among others, was taken and starved to death or tortured to death for no reason at all."

Rumours of torture

For decades, one of the signatures of the Assad regime, Bashar and his father before him, has been a vast network of prisons and detention centres — places where torture is rumoured to be routine.

In August 2014, concealed by dark glasses and a blue hood, Caesar testified in secret to a United States congressional committee about what he'd seen. He'd hoped his evidence would have resulted in political action. But three years later, Bashar al-Assad seems more securely in power than ever.

In February, he was asked about the Caesar photos in an interview with Yahoo News.

"Who verified they're not edited and photoshopped and so on?" Assad asked.

"If you take these photos to any court in your country, could they convict any criminal regarding this, could they tell you what this crime, who committed [it]?

"If they don't have this full picture, you cannot make judgment. It's just propaganda. It's just fake news. They want to demonize the Syrian government."

Clues on the photos

But there is one thing about the pictures that isn't so easily dismissed — the machinery of Assad's own bureaucracy left clues.

Many of the photos contain a series of arabic numbers that Caesar says are important.

"The top number that appears is the number of the individual when they were detained, so once you enter prison you no longer have a name, you go by this number that you are assigned," he says.

"The number in the middle is the number of the intelligence branch and ... that's the intelligence branch where this individual was held and tortured to death…. It shows the specific branch responsible for the death."

Knowing the specific branch is critical to lawyers who are trying to build a criminal case against Assad and his regime — it helps identify those responsible.

Chris Engels is the deputy director of investigations and operations for the Commission for International Justice and Accountability (CIJA). (CBC/The Fifth Estate)

"The numbering system … allows us to, in some cases, look at material we have collected and saved from the field and look at the Caesar photos and cross-check" them, said Chris Engels, deputy director of investigations and operations for the Commission for International Justice and Accountability (CIJA).

3 tonnes of documents

CIJA is one of several human rights groups trying to document abuses by the Assad regime in the hopes of one day bringing it to trial.

Funded in large part by the Canadian government, CIJA focuses on obtaining documents generated by the Syrian regime itself. In five years, the organization has smuggled 700,000 documents out of Syria. The three tonnes of paper are stored at a secret location in Europe.

Bill Wiley, the Canadian legal expert and executive director of CIJA, says among the documents is clear evidence of war crimes — murder, torture and crimes against humanity.

"We've got eight or nine prosecution case files ready which go to the highest reaches of the Syrian regime including the president, Mr. Assad, and all we need now is a court and a public prosecutor to take over these files and proceed."

Bill Wiley is a Canadian legal expert and the executive director of the Commission for International Justice and Accountability. (CBC/The Fifth Estate)

But the problem is that there is no court. Efforts to refer Syria to the International Criminal Court in The Hague have been blocked by Syria's allies — primarily Russia.

Some European countries have launched national investigations, but those are more limited and have yet to be tested in court.

'It's been depressing'

After all the death, destruction and terror, Caesar says he feels betrayed.

He told The Fifth Estate he risked his life to get his photographs out, thinking they would change everything and that Assad would finally be forced to go.



"To be honest with you, it's been depressing to see this sort of disappointing lack of action by the international community as they view this evidence of war crimes," Caesar says.



"I'm pleading with [the] international community that thousands and thousands and thousands more remain in Assad jails, facing the same fate that the people in my photographs have faced. And it is our responsibility to save the rest.

"We couldn't save these individuals but we must do everything we can to ensure that the rest of the people who sit in Assad jails do not face the same horrible fate."

Caesar and his colleagues were recently awarded the City of Nuremberg's 2017 Nuremberg International Human Rights Award for their "courage in bringing the systemic torture and mass murders in Syria to the attention of the world public," the organization said in a media release.