WASHINGTON (AP) — Graphic images of emaciated and bloodied corpses in the Syrian civil war were presented to uncharacteristically silent members of Congress Thursday as a former military photographer testified about the signs of savagery he witnessed.

Codenamed “Caesar,” the man appeared before the House Foreign Affairs Committee in disguise, his face concealed by a blue hooded raincoat, hat and glasses. Before defecting from Syria last year, he smuggled out 55,000 photos showing more than 10,000 bodies.

Fearing for his safety, the man whispered to an interpreter, who repeated his words aloud in English.

He said he witnessed a “genocidal massacre.”

“I am not a politician, and I don’t like politics. Neither am I a lawyer,” Caesar said. But he said he couldn’t simply continue doing his job taking pictures of the dead as the number of bodies being brought in by military and intelligence officials multiplied after anti-government protests erupted in 2011.

The corpses included young children, the elderly, women and his own neighbors and friends, though he couldn’t tell their families about what he saw.

“Death would have been my fate if the regime found out,” he said.

The State Department arranged Caesar’s trip to the United States but did not provide his name to any members of Congress.

No audio or video recordings were permitted in the hearing, as Republicans and Democrats alike took the opportunity to question Caesar about what he saw and call on the Obama administration to adopt a more forceful policy to overthrow Syrian President Bashar Assad’s government. Caesar’s photographs were enlarged and displayed on poster board in the background and on television monitors mounted on each side of the room. They showed images of people whose necks had been slashed, eyes gouged out and foreheads ripped open.

“This is happening right now in Syria as we speak, and we can do more to stop it,” said Rep. Eliot Engel, the committee’s top Democrat.

The hearing occurred as Congress continued to weigh action by President Barack Obama to significantly expand US training and arming of Syria’s rebels. He has proposed spending $500 million for a Pentagon-run program that would broaden a previously covert effort to equip vetted, moderate rebels fighting Assad’s forces and an expanding Sunni extremist insurgency that has spread to Iraq.

Lawmakers in both chambers, however, have been trying to get more details of the plan. Last week, for example, Democratic Sen. Mark Pryor questioned whether the administration could determine which groups are moderate in Syria as the 3-year-old civil war grinds on with 170,000 dead. He said it would be impossible to keep track of the weapons.

Dovish Democrats and libertarian-leaning Republicans in both chambers are worried about the US being drawn deeper into another conflict in the Middle East, while hawks have criticized the administration for doing too little, too late.

Testifying alongside Caesar, Fred Hof, a former State Department point-man on Syria, criticized the president for not taking stronger action a couple of years ago. But even as he said he wished different decisions had been made in 2012, he said he hoped he wasn’t in a situation a few years from now contemplating what might have been done in 2014.

Caesar said that more than 150,000 people are still incarcerated by Assad’s government. Referencing his pictures, he warned that a similar fate could befall all of them if the United States fails to intervene in a manner similar to US intervention in the Balkans in the 1990s. Assad and his allies, he told the panel’s members, “are way weaker than you believe.”

The photos were previously shown to the UN Security Council in April. At the time, Syria’s Justice Ministry dismissed them and an accompanying report as “lacking objectiveness and professionalism.” It said some of the people were militants killed in battle and that others were killed by militant groups. An investigation of Caesar’s photos was funded by Qatar, a main backer of the Syrian rebels, prompting some outside skepticism, too.

The forensic team that investigated thousands of Caesar’s images included David Crane, a Syracuse University law professor who was chief prosecutor for the international war crimes tribunal that indicted Liberian leader Charles Taylor. Crane said he confirmed the veracity of the photos he likened to images of Auschwitz. He said they show clear war crimes and crimes against humanity.

“We rarely get this smoking gun evidence,” Crane said.

Copyright 2014 The Associated Press