of human rights and fundamental freedoms has occurred in any territory under its jurisdiction.” 72. An investigation must respect a number of essential requirements in order to be effective. It must be: a)  adequate, i.e., capable of leading to the identification and punishment of those responsible; b)  thorough, i.e., comprehensive in scope and – among other things – capable of identifying any systematic failures that led to the violation; c)  impartial and independent, i.e., those responsible for carrying out the investigation must be impartial and independent from those implicated in the events; d)  prompt, i.e., the investigation must be commenced swiftly and be completed within a reasonable time; e)  and there should be a sufficient element of public scrutiny of the investigation or its result to secure accountability, which is particularly important to “maintain public confidence in the authorities’ adherence to the rule of law and to prevent any appearance of collusion in or tolerance of unlawful acts”.98 73. Concerning investigations into allegations of excessive use of force, torture and other ill-treatment, as well as other examples of abuse of power by law enforcement officials, UN Treaty Bodies regularly call on states to establish, where they do not exist, independent bodies with authority to receive and investigate complaints in relation to such acts.99 Furthermore, the Council of Europe Committee of Ministers has also recommended states to consider giving or, where appropriate, strengthening the competence and capacity of NHRIs to receive, consider and make recommendations for the resolution of complaints by human rights defenders about violations of their rights.100 Under all circumstances, complainants must be protected from any ill-treatment, intimidation or reprisals as a consequence of their complaints.101 This also means that human rights defenders should not face retaliatory investigations or prosecution against them for bringing complaints. 98  “Guidelines of the Committee of Ministers of the Council of Europe on eradicating impunity for serious ­human rights violations”, section VI. Criteria for an effective investigation, adopted on 30 March 2011, <https://wcd.coe.int/ViewDoc.jsp?id=1769177>. 99  See, for example, “Concluding Observations of the UN Committee against Torture on Kyrgyzstan”, UN Doc. CAT/C/KGZ/CO/2, 20 December 2013, para. 6; “Concluding Observations of the UN Committee against Torture on Tajikistan”, UN Doc. CAT/C/TJK/CO/2, 21 January 2013, para. 15; “Concluding Observations of the UN Committee against Torture on Armenia”, UN Doc. CAT/C/ARM/CO/3, 6 July 2012, para. 12; “Concluding Observations of the UN Committee against Torture on Lithuania”, UN Doc. CAT/C/LTU/CO/2, 19 January 2009, para. 14; and “Concluding Observations of the UN Human Rights Committee on Azerbaijan”, CCPR/C/AZE/ CO/3, 13 August 2009, para. 11. 100  Op. cit. “Declaration of the Committee of Ministers on Council of Europe action to improve the protection of human rights defenders and promote their activities”, para. 2(v). 101  See “Concluding Observations of the UN Committee against Torture on Tajikistan”, UN Doc. CAT/C/TJK/ CO/2, para. 15. Guidelines on the Protection of Human Rights Defenders 47