For the last four years, the Transitional Justice Working Group's mapping project has interviewed North Korean escapees living in South Korea in an effort to determine where the victims of the regime have been killed and buried. This talk will present the mapping system we've developed, the challenges we've faced building it, and how many of these challenges have been partially or fully addressed using free and open source software and data (FOSSD). Our first two mapping reports and a few data sets of sites suspected of containing documents can be found at https://en.tjwg.org/mapping-project-north-korea/.