Documentary archives, human remains, and witness testimony are often critical to transitional justice court proceedings and peace-building projects after mass violence. But what happens when those forms of evidence are missing? Can art stand in for the dead? Considering the use of art in Vann Nath's testimony in the trial of Kaing Guek Eav (Duch) in the Extraordinary Chambers in the Courts of Cambodia, in this paper, I argue that in the first case for the ECCC, Vann Nath's art performed a similar role to that of human remains in other trials, providing evidence and proof of human rights violations including torture, cruel and inhuman treatment, arbitrary detention, and mass killing, while also activating affect (drawing on Hughes). As such, it provided a form of social proof, in a way similar to the human remains retained from the genocide and displayed across Cambodia. Both human remains and art draw on materiality and emotion as a means of proving violence. Positioning it as such prompts a reconsideration of the role of art in transitional justice: as well as being needed in cases where other visual evidence does not exist, art, with its ability to mobilize and communicate linguistically incommunicable affect, can be part of the evidentiary infrastructure in and of itself. Considering the place of art in trials after mass violence makes us rethink what evidence is and does. Ultimately, my argument is that to those who survive genocide or other mass violence social proof of atrocities, as provided by art, is as important as evidence deemed legally admissible to court.