2.3.7 Where requested, public authorities should be required to register all representations which could be deemed to constitute complaints. An appropriate form should be introduced for acknowledging receipt of each complaint and confirming that the matter will be pursued. 2.3.8 Inspection and monitoring mechanisms empowered to determine representations of ill-treatment should also adhere to these Guidelines. 2.3.9 Individuals who come into contact with law enforcement authorities should be fully informed of their rights that counter ill-treatment and of the mechanisms and procedures that are available to them. III. The investigation: grounds and purposes 3.1 Grounds for investigation 3.1.1 The obligation to initiate an investigation arises when the competent authorities receive a plausible allegation or other sufficiently clear indications that serious ill-treatment might have occurred. An investigation should be undertaken in these circumstances even in the absence of an express complaint. 3.1.2 It is mandatory to conduct an investigation when confronted with credible accounts of physical or psychological abuse, excessive use of force, or other forms of serious (deliberate) ill-treatment. 3.1.3 Particular care must be taken in probing possible racial or other discriminatory motives that may lie behind ill-treatment. 3.1.4 Investigations into ill-treatment which do not fall into the mandatory categories must meet the same standards on effectiveness. 3.1.5 Decisions to terminate or to refuse to initiate investigations into ill-treatment can be taken only by an independent and competent authority upon thorough and prompt consideration of all the relevant facts. Such decisions should be subject to appropriate scrutiny and challengeable by means of a public and adversarial judicial review process. 3.2 Principal purposes of investigations 3.2.1 Effective investigation requires genuine efforts to be made to properly establish the relevant facts and, where appropriate, to identify and punish those responsible for ill-treatment. 3.2.2 Investigating authorities could also be tasked with identifying and implementing measures to prevent recurrences of ill-treatment. Effective investigation of ill-treatment – Guidelines ► Page 12