System crimes (as with most organized crime) are generally characterized by a division of labour between planners and executants, as well as arrangements in structure and execution that tend to make connections between these two levels difficult to establish. They are complicated by the fact that they are often (though not always) committed by official entities and frequently with the involvement of people who were, or may remain, politically powerful. The crimes usually affect large numbers of victims, and these issues of scale and context make investigations more logistically difficult. On the other hand, system crime investigation is facilitated by the fact that official bodies generally operate under an institutional framework with direct lines of reporting and accountability. This structure provides a useful basis for developing lines of investigation, which allows for inferences to be drawn regarding the authorization of crimes in the absence of any direct evidence. Investigative techniques for system crimes differ from those relating to ordinary crimes. The prosecutor’s work in investigating and presenting most ordinary crimes can be likened to that of a film director, whose task is to describe clearly how a particular event occurred, and whose main concern is describing the carrying-out of a specific criminal act. The clearer the description, the easier it will be for the court to determine responsibility. However, the investigation of system crimes requires an approach closer to that of an engineer. The task is not simply to describe the carrying-out of the criminal act, but to elucidate the operation of the elements of the machinery. System crime investigation, whether in relation to a series of criminal acts or an isolated one, requires a detailed exploration of the system itself, and not merely of the results, which are manifested in the underlying crimes that constitute the so-called crime base (e.g., murder, torture, rape, deportation). However, few investigative bodies have developed the necessary techniques and resources to investigate system crimes effectively. 1. The need for a multidisciplinary investigation System crimes are most often committed by State security forces (army or police) or by insurgent or paramilitary organizations. Effective investigation requires appropriate analysis of the ways in which such organizations are legally required to work, as well as how they actually operated during the time in question. Lawyers may lack all the skills necessary to carry out such analyses, and significant input from other experiences and disciplines can be very beneficial. Such investigations require analysis that presents persuasive evidence in relation to: • T he particular practices of military and paramilitary organizations. Training, command structures, logistics, communications systems, munitions supplies and disciplinary procedures may all be relevant to investigations. Expert guidance is often necessary if investigations are to be carried out effectively. 12