Stephen Rapp, the State Department’s ambassador-at-large for War Crimes and director of the Office of Global Criminal Justice, has reviewed large sections of a huge collection of photos and written records of Syrian government atrocities smuggled out of the country by a former military photographer known as “Caesar.” Rapp spoke about the evidence at a July 3 event at the Atlantic Council in Washington.

“This is solid evidence of the kind of machinery of cruel death that we haven’t seen frankly since the Nazis,” he said. “If it is as it appears thus far, we’re talking about more than 10,000 individuals being killed in custody over the period from 2011 to 2013, including largely men but also some very, very young men and boys and women… It’s shocking to me, as a prosecutor—I’m used to evidence not being so strong.”…

Another former war crimes prosecutor who has reviewed some of the evidence tells The Daily Beast that he believes the photos indicate at least indirect “Russian government responsibility” for the atrocities.