o Changes of behavior such as aggression, social isolation or risktaking behavior o Medically unexplained physical complaints. • When a set of symptoms persists for more than a month after a potentially traumatic event and if it causes difficulty with their daily functioning, the victim or witness may have developed posttraumatic stress disorder (PTSD). 27 • Traumatic events can also cause other mental, neurological or substance use conditions. 28 If unofficial investigators become aware that a victim or witness may be suffering from post-traumatic stress disorder or another mental, neurological or substance use condition, they should provide the victim or witness with a referral to professional assistance (see previous section). Gathering Information and Re-Traumatization Building rapport is the first step to building a sensible relationship with victims and witnesses. It is important to try to understand and relate to the victim’s or witness’ reality when preparing for and conducting interviews with them. Unofficial investigators should seek information about the victim’s or witness’s understanding of the occurrences and subsequent experience in advance of any documentation exercise or interview. 29 Be aware that they may: • deny they are a victim or witness; • be afraid of what will happen to them; • feel that it is their fault that they are in this situation; • be afraid of you and what the documenting of their statements will cause; • be distracted, angry, reluctant, or concerned about their own needs; • have concerns about their safety and privacy, particularly if the interview is observed by others; 27 World Health Organization and United Nations High Commissioner for Refugees, mental health Gap Action Programme Humanitarian Intervention Guide (mhGAP-HIG): Clinical management of mental, neurological and substance use conditions in humanitarian emergencies, 14 (2015), available at http://apps.who.int/iris/bitstream/10665/162960/1/9789241548922_eng.pdf?ua=1. 28 World Health Organization and United Nations High Commissioner for Refugees, mental health Gap Action Programme Humanitarian Intervention Guide, 27 (2015). 29 Office for Victims of Crime Training and Technical Assistance Center, Human Trafficking Task Force E-Guide, 5.3 Trauma-Informed Victim Interviewing, available at https://www.ovcttac.gov/taskforceguide/eguide/5-building-strong-cases/53-victim-interviewpreparation/trauma-informed-victim-interviewing/. 34