Undertaking Effective Investigations A Guide for National Human Rights Institutions 6. TIMING OF INTERVIEWS This is the golden rule for all investigations: Get the most comprehensive a statement possible, as quickly as possible. The best evidence is the freshest. Memories fade or are tainted, inadvertently or otherwise. Some academic studies have shown that the longer the passage of time before a statement is taken, the less likely it is to be accurate. The number of times a person recalls an event is also important. A study by Northwestern University found that an individual’s “memory of an event can grow less precise – even to the point of it being totally false – with each retrieval”.38 The memory is rewritten every time it is remembered, eventually distorting the original memory. In many cases, it is prudent to interview witnesses immediately after each other or, if there are enough investigators available, to interview witness at the same time. This minimizes the possibility of actual or perceived collusion. What an investigator does not want is an interviewee sharing the questions they have been asked with a fellow witness who has yet to be interviewed. It is best practice to interview witnesses as soon as possible after an incident. However, there are cases where a witness is not, or claims not to be, physically or emotionally fit to give an immediate statement. In most cases, the trauma is obvious. However, not all such claims should be taken at face value. If there are grounds to suspect that the claim is not genuine, the investigator should use their own judgment, meet with the person if possible and, where necessary, ask for medical evidence to support the claim. WHEN TO INTERVIEW WITNESSES In Canada in 2008, during a bus journey across the Prairies, a passenger, who turned out to have a mental illness, drew a sharp knife and decapitated the passenger who was asleep in the seat next to him. The two had never met before. There were 30 other passengers on the bus. They managed to get off and lock the bus door behind them. They then watched in horror as the man walked up and down the bus, cutting pieces of flesh from the victim’s body, including one of his ears, and eating them or stuffing them in his pockets. Police arrived shortly afterwards. They arrested the man. They escorted the witnesses to a nearby town, segregated them and interviewed them immediately, one by one. 7. THE ORDER IN WHICH INTERVIEWS ARE CONDUCTED Deciding the order in which to interview witnesses depends entirely on the circumstances of the case. Generally, but not always, the process should start with the alleged victim or complainant. This provides an opportunity to get more details about the complaint, including identifying possible investigative avenues and obtaining any documents or other evidence that the complainant may have not yet provided. The next step should be to interview any independent witnesses, starting with those closest to the event or issue. 38 70 “Your memory is like a telephone game”, Marla Paul, Northwestern University News; 19 September 2012; available at https:// news.northwestern.edu/stories/2012/09/your-memory-is-like-the-telephone-game. The paper was published in the Journal of Neuroscience in September 2012.