anguishes, i would have to pray that a tear does not come down my face, because if they saw one tear. if they saw one expression on my face that showed sympathy, then i would be killed as with my family. >> how did you do that? >> i don't know. >> reporter: in 2013, he finally fled and brought with him what the fbi confirmed as authentic. and the state department's ambassador for war crimes described stronger evidence than what existed against the nazis. the syrian government has denied responsibility and called the photos fake. caesar made his first trip to capitol hill in 2014. testifying before congress under cover in the exact same disguise he used for our interview. >> i honestly thought that if i could have the courage to go for the years that i did, doing the work that i did endangering my life every single day, that once i came out and showed the world what i had that the entire