The use of Forensic Sciences in the scientific documentation of human rights vio lations has created new challenges for the professionals involved in the task. These are not questions of understanding ordinary crimes, but of working on massive cases, in which the state tends to be the main perpetrator. In processes of political violence, the disappearance of a loved one is agonizing for the family, given the uncertainty about whether the person is alive or dead. The forensic scientists as well the concerned lawyers must therefore consider, before beginning an investigation, the psychological, judicial, political, economic and humanitarian consequences of exhuming human remains and trying to identify them. What first appears as a clear-cut scientific, technical operation may have complex and ambiguous boundaries as well ethical dimensions.