The Guardian has a horrific first-hand account by “Caesar,” a former Syrian military photographer who managed secretly to copy and smuggle out thousands of photographs of the tortured and starved bodies of prisoners of the Assad government– mainly regime opponents arrested since the revolt against the regime began in 2011.
Garance le Caisne, who obtained the account from Caesar, quite correctly describes the operation against the prisoners as a “death machine.” As she writes:
The terrorists of Islamic State proclaim their atrocities on social networks; the Syrian state hides its misdeeds in the silence of its dungeons.
It is quite right that Caesar provided the smuggled photos to the US Holocaust Museum in Washington, DC, which documents current atrocities as well as historical ones. If you have the stomach for it, you can see some of the images here: