Genocide was first recognised as a crime under international law by the United Nations General Assembly in 1946. The crime was then codified by the 1948 Convention on the Prevention and Punishment of the Crime of Genocide. The heart of the offence is targeted actions aimed at the destruction of a particular group of people. Andrew Cayley has investigated and prosecuted genocide in both Bosnia-Herzegovina and Cambodia. In this lecture he will explore the origins of the crime and share his experiences of investigating and prosecuting the 'crime of crimes'.