Telford Taylor, a Nuremberg proceedings prosecutor, observed in his Final Report that the issue of genocide and crimes against humanity and their investigation "was far bigger and far more difficult of solution than anyone had anticipated." The experience of more recent cases, and particularly the UN ad hoc tribunals, has confirmed that investigating crimes of this kind is far more complex a duty than the public opinion and the policymakers may think when the call for justice is made. The investigation of these crimes raises hard questions of method at different levels, from epistemology and cognitive psychology, to forensic sciences and resource management. The hardest investigative challenges are not related to the criminal act as such, which is often a blatant and notorious phenomenon, but to the questions on specific intent and individual responsibility, particularly for those suspects at higher levels of authority.

Early precedents...