The two defectors, who live in an undisclosed location abroad, made their case on Monday to small group of human rights experts and reporters in a private meeting at the United States Holocaust Memorial Museum, and in a brief interview afterward. Neither photographs nor recordings of the session were allowed, to help protect their identity. They and their extended family are presumed to be at risk from the Syrian government and its agents.
Caesar has supporters in Congress, but whether he will be able to make inroads with the Trump administration is far from clear. The defectors spoke Monday with Michael Ratney, who has served as the United States’ envoy on the Syria crisis, and they are scheduled to meet this week with senior aides at the National Security Council.
But no meeting has been set with Lt. Gen. H.R. McMaster, Mr. Trump’s national security adviser, or with the top echelons of the State Department or Pentagon.
In a retrospective moment, the two defectors said they did not regret taking enormous risks to spirit the photos out of Syria — even though they had discovered that the international community was better at expressing outrage than agreeing on measures to quell the fighting and to press for a more inclusive government that did not include Mr. Assad.
For years, Caesar explained, his duties as a police photographer required him to document bodies that were often battered beyond recognition, a gruesome procedure mandated by the Syrian government. Determined to expose the torture and killing to the world, he smuggled thumb drives with the digital photos in his shoes and socks as he passed through government checkpoints.
Nor was the government the only worry, he said. For a while, the opposition Free Syrian Army had controlled much of his neighborhood, and Caesar had been afraid that he would be in danger if the rebels found out he worked for the police. He handled that risk by making a fake civilian ID.
By the end of 2013, he said, he had enough photos to document the murder and torture of more than 11,000 people and was ready to flee and make the evidence known. Caesar said his greatest worry was that the government would retaliate against his extended family.
“My life is not more valuable than the many who are being killed inside the country,” he said. “I died a hundred times a day. Looking at those bodies broke my heart.”
Navigating American policy on Syria has not been easy for the two defectors. While Mr. Obama declared that the Assad regime had lost the legitimacy to lead the nation and authorized a covert program to assist Syrian rebels, he was reluctant to take more direct action to compel the Syrian president to hand over power.
The Trump administration has neither spoken out forcefully on the Syria crisis nor promised fresh action, beyond a pledge to establish safe zones to try to stem the flow of Syrian refugees.
Mr. Trump indicated during the campaign that he has little interest in confronting Mr. Assad and has flirted with the idea of partnering with Russia, one of the Syrian government’s main backers, to press the military campaign against the Islamic State. At the same time, however, Mr. Trump’s vow to establish safe zones has given the defectors something of an opening.
Establishing safe zones in the northern and southern parts of the country would do much to mitigate the suffering of the Syrians who oppose Mr. Assad, Sami said.
American lawmakers, meanwhile, have been promoting legislation that would impose sanctions on anyone who provides financing or does business with the Assad government, which has also given the defectors a measure of hope. The legislation also calls for an assessment of how to set up safe zones or no-fly zones, and for an investigation of war crimes.
“The United States does not need to send troops,” Sami said. “It could sanction the Central Bank of Syria.”