This paper focusses on the forensic work put on display at Londres-38, a building in Santiago Chile designated as a National Monument, which once functioned as a torture and extermination centre under Pinochet's dictatorship. Striving to avoid conventional memorial practices, or didactic strategies that would morbidly represent the past horror, Londres-38 curatorially opts for very few educational props, so that visitors can have a peculiarly direct encounter with the materiality of the building. The paper engages with one of the few displays employed at Londres-38: a time-looped video detailing the forensic work undertaken on a small washroom. Despite the years that have passed, remaining within its walls, floors, and on the surfaces of the National Monument are material traces left by the detainees-disappeared: scratches and inscriptions, as well as DNA, that are still being forensically harvested. The paper discusses how the video exhibit documents a pedagogical performance of how the unperceived can come to light, how the erasure of the violent past can be made to re-appear as a matter of public concern through a certain sensibility to materiality that is unique to forensics. At issue in the paper is the curatorial-pedagogical strategy employed that invites us to immerse and try out for ourselves the forensic sensibility that tends to and gazes at the materiality of the building in a particular way so that the embedded evidence therein can come to matter and move us to hear the unsettled call for justice in our present.