The prohibition of slavery and forced labour (Article 4 of the Convention) The prohibition of slavery and forced labour entails a procedural obligation to carry out an effective investigation into situations of potential trafficking in human beings. The right to liberty and security (Article 5 of the Convention) Procedural safeguards derived, inter alia, from the right to liberty and security require that states conduct effective investigations into credible claims that a person has been deprived of his or her liberty and has not been seen since. The right to respect for private and family life (Article 8 of the Convention) States have a duty to effectively investigate credible claims of serious violations of the rights enshrined in Article 8 of the Convention where the nature and gravity of the alleged violation so requires, in accordance with the case law of the Court. 2. Where an arguable claim is made, or the authorities have reasonable grounds to suspect that a serious human rights violation has occurred, the authorities must commence an investigation on their own initiative. 3. The fact that the victim wishes not to lodge an official complaint, later withdraws such a complaint or decides to discontinue the proceedings does not absolve the authorities from their obligation to carry out an effective investigation, if there are reasons to believe that a serious human rights violation has occurred. 4. A decision either to refuse to initiate or to terminate investigations may be taken only by an independent and competent authority in accordance with the criteria of an effective investigation as set out in guideline VI. It should be duly reasoned. 5. Such decisions must be subject to appropriate scrutiny and be generally challengeable by means of a judicial process. VI. Criteria for an effective investigation In order for an investigation to be effective, it should respect the following essential requirements: Adequacy The investigation must be capable of leading to the identification and punishment of those responsible. This does not create an obligation on states to Effective investigation of ill-treatment – Guidelines ► Page 124