tocols governing the chain of custody and other such considerations. Even in purely domestic initiatives, ad hoc international assistance may be sought in the preservation of evidence, for instance in the engagement of a forensic capability.30 United Nations employees that witness or investigate crimes should be aware of the fact that they may be called to testify.31 United Nations reports compiled by bodies such as expert groups that have conducted investigations on the ground may be admissible in subsequent criminal trials. Likewise, those engaged in compiling such reports may be called as experts,32 as may other United Nations representatives, depending on the applicability of the Convention on the Privileges and Immunities of the United Nations or any other ad hoc arrangements.33 Such testimony is usually taken in conditions that respect the confidentiality and sensitive nature of the testimony, such as in closed session or under other controlled conditions.34 3. The significance of analysis of patterns in the investigation of system crimes While reconstructing the crime base is essential to the prosecution of system crimes, analysis must play a central role. A lack of emphasis on analysis will likely result in a more expensive process that takes longer, addresses a smaller number of victims and has a diminished prospect for proving participation of those behind the scenes. Part of the goal of analysis will be to identify patterns. A “pattern” refers to a set of events that, by their frequency, location and nature, imply some degree of planning and centralized control. The use of patterns can help prove that a particular crime was part of a planned process. The legal inferences that can be drawn from the use of patterns in evidence will depend on the facts 30 Discussions for the formation of a regular international capacity for this, in the form of “justice rapid response teams”, are currently under way among various Governments. 31 Regarding the International Criminal Court, it appears that the Office of the Prosecutor will approach the issue of United Nations staff testimony with great caution and, in general, seek to use it only if the information cannot be obtained from another source and is deemed vital to the case. Nevertheless, one has to remember that the defence also has the right to call United Nations staff. 32 In the ICTY case of Kovacevic, the Prosecution called one of the members of the United Nations Commission of Experts for the former Yugoslavia established under Security Council resolution 780. The Trial Chamber allowed the evidence on the reasoning that she was analogous to a contemporary historian and that she had made a study of the material and was qualified to testify on it. However, the Trial Chamber specified that the evidence was hearsay, that the defence would be able to cross-examine, and that the accused would not be convicted on the basis of such evidence alone. 33 F or instance, the International Criminal Court has concluded its own relationship agreement with the United Nations to regulate these issues. Specifically, it currently states in article 16 that: “If the Court requests the testimony of an official of the United Nations or one of its programmes, funds or offices, the United Nations undertakes to cooperate with the Court and, if necessary and with due regard to its responsibilities and competence under the Charter and the Convention on the Privileges and Immunities of the United Nations and subject to its rules, shall waive that person’s obligation of confidentiality.” 34 F or instance, several prominent United Nations witnesses have given evidence before the ad hoc Tribunals, including General Morillon, former commander of the United Nations Protection Force (UNPROFOR), and General Dallaire, former commander of the United Nations Assistance Mission in Rwanda (UNAMIR). 15