IV. Measuring effectiveness: the key criteria 4.1 Independence and impartiality 4.1.1 Officials involved in conducting investigations and all decision-makers cannot be part of the same public authority as the officials who are the subject of the investigation and must be otherwise independent from those implicated in the facts being investigated. 4.1.2 This requires independence in practical terms, not only the absence of hierarchical or institutional connections. 4.1.3 Officials involved in conducting investigations and all decision-makers must be impartial. In particular, they should not be involved in investigations or decisions regarding the alleged victims of the case in question. 4.2 Thoroughness 4.2.1 Investigations into ill-treatment should involve the taking of all reasonable steps to secure evidence concerning the relevant incident(s). 4.2.2 The typical inventory of required investigative measures and evidence includes: – detailed and exhaustive statements of alleged victims obtained with an appropriate degree of sensitivity; – appropriate questioning and, where necessary, the use of identification parades and other special investigative measures designed to identify those responsible; – confidential and accurate medical (preferably forensic) physical and psychological examinations of alleged victims. These should be carried out by independent and adequately trained personnel capable of identifying the causes of injuries and their consistency with the allegations; – other medical evidence, including records from places of detention and health care services; – appropriate witness statements, possibly including statements of other detainees, custodial staff, members of the public, law enforcement officers and other officials; – examination of the scene for material evidence, including implements used in ill-treatment, fingerprints, body fluids and fibres. Examinations should involve the use of forensic and other specialists able to secure and examine the evidence, create appropriate sketches, and/or reconstruct the relevant events; and Guidelines on international standards ► Page 13