PART II 7 INVESTIGATION promise evidence. Investigations should be carried out in a way that is fair and even-handed; all evidence should be equally considered, whether it supports or contradicts the initial allegation under investigation. If an investigation establishes that no human rights violation has occurred, the case can be closed, meaning that the mission will not continue to work on the case. If the investigations or inquiries establish the likelihood that there has been a human rights violation, the mission should report its conclusions (see Chapter 8) and make recommendations for further action, in line with Part III. In either instance, depending on the particularities of the case, it must be determined how pieces of evidence, confidential documents, etc. collected during the investigation should be treated. 7.1 CORROBORATION An investigation seeks to verify, or corroborate, whether a complaint of an alleged human rights violation is valid. For new information to be corroborating, it should be collected from independent sources and fit into the context emerging from other materials that have been amassed.  It may be possible to corroborate the information received by speaking to the family, friends, and neighbours of the apparent victim. It is important that witnesses are interviewed separately;  It may also be possible to take note of physical or psychological symptoms that are observed during the interview;  If the victim has a defence lawyer, this can usually be an important source of information. Corroborating some types of allegations requires particular expertise that may or may not be available to an OSCE mission. An obvious example would be a report of the existence of a mass grave. Allegations of this type have faced OSCE field operations in the past and are sufficiently serious that they should not be ignored even by the smallest missions. However, while it may be possible for an OSCE staff member to visit a site (see Section 7.2) of an alleged mass grave, it would require a forensic expert to excavate and interpret the evidence. Any such effort would also require the co-operation of the host government. Serious investigations or other types of issues may also require expertise that is not available at 68