The number of academic writings on international criminal procedure is growing rapidly. Nevertheless, the investigation phase has so far received less attention than the trial phase itself. The importance of investigative actions for the further proceedings is not yet reflected to the full extent in academic writings on international criminal proceedings. This book seeks to cover this gap. It examines the existing law and practice of the different international(ised) criminal courts and tribunals with regard to the conduct of investigations in order to identify any (emerging) rules of international criminal procedure. More precisely, it enquires whether, notwithstanding their nature of 'self-contained regimes', these institutions have adopted certain common rules. Additionally, it aims to examine the fairness of the law and practice of the different international(ised) criminal courts and tribunals with regard to the conduct of investigations.