The purpose of this article, on the basis of a specific Dutch example, is to discuss some methodological problems that criminologists and/or criminal lawyers face when dealing with atrocities committed in the past. Can we legitimately apply contemporary concepts to describe/explain historical events? Or are we guilty of a 'sin' of anachronism because we ascribe meanings to actions that these did not (or could not) have at the time they were performed? Generally, most criminologists turn their attention to contemporary phenomena and, therefore, do not have to worry about the time dimension. However, when studying international crimes, which are often historical events, this should not happen. When dealing with crimes of a previous regime,. we should be aware of some methodological problems linked to the use of (contemporary) concepts to describe and explain events of the past. Legal scholars may also encounter problems when applying contemporary concepts to past atrocities.