–4– 33. An investigation into possible ill-treatment by public officials must comply with the criterion of thoroughness. It must be capable of leading to a determination of whether force or other methods used were or were not justified under the circumstances, and to the identification and, if appropriate, the punishment of those concerned. This is not an obligation of result, but of means. It requires that all reasonable steps be taken to secure evidence concerning the incident, including, inter alia, to identify and interview the alleged victims, suspects and eyewitnesses (e.g. police officers on duty, other detainees), to seize instruments which may have been used in ill-treatment, and to gather forensic evidence. Where applicable, there should be an autopsy which provides a complete and accurate record of injury and an objective analysis of clinical findings, including the cause of death. The investigation must also be conducted in a comprehensive manner. The CPT has come across cases when, in spite of numerous alleged incidents and facts related to possible ill-treatment, the scope of the investigation was unduly circumscribed, significant episodes and surrounding circumstances indicative of ill-treatment being disregarded. 34. In this context, the CPT wishes to make clear that it has strong misgivings regarding the practice observed in many countries of law enforcement officials or prison officers wearing masks or balaclavas when performing arrests, carrying out interrogations, or dealing with prison disturbances; this will clearly hamper the identification of potential suspects if and when allegations of ill-treatment arise. This practice should be strictly controlled and only used in exceptional cases which are duly justified; it will rarely, if ever, be justified in a prison context. Similarly, the practice found in certain countries of blindfolding persons in police custody should be expressly prohibited; it can severely hamper the bringing of criminal proceedings against those who torture or ill-treat, and has done so in some cases known to the CPT. 35. To be effective, the investigation must also be conducted in a prompt and reasonably expeditious manner. The CPT has found cases where the necessary investigative activities were unjustifiably delayed, or where prosecutorial or judicial authorities demonstrably lacked the requisite will to use the legal means at their disposal to react to allegations or other relevant information indicative of ill-treatment. The investigations concerned were suspended indefinitely or dismissed, and the law enforcement officials implicated in ill-treatment managed to avoid criminal responsibility altogether. In other words, the response to compelling evidence of serious misconduct had amounted to an “investigation” unworthy of the name. 36. In addition to the above-mentioned criteria for an effective investigation, there should be a sufficient element of public scrutiny of the investigation or its results, to secure accountability in practice as well as in theory. The degree of scrutiny required may well vary from case to case. In particularly serious cases, a public inquiry might be appropriate. In all cases, the victim (or, as the case may be, the victim's next-of-kin) must be involved in the procedure to the extent necessary to safeguard his or her legitimate interests. 37. Disciplinary proceedings provide an additional type of redress against ill-treatment, and may take place in parallel to criminal proceedings. Disciplinary culpability of the officials concerned should be systematically examined, irrespective of whether the misconduct in question is found to constitute a criminal offence. The CPT has recommended a number of procedural safeguards to be followed in this context; for example, adjudication panels for police disciplinary proceedings should include at least one independent member.