11 cruel, inhuman or degrading treatment or punishment.41 Such investigations shall be impartial, independent and effective, and shall be conducted in a prompt and transparent manner. All law enforcement officials shall cooperate fully with any such investigation, and investigators shall be able to compel the production of evidence. Such investigative powers should be given to independent police oversight mechanisms which strengthen the accountability of law enforcement agencies and officials. Medical professionals involved in any investigation shall act in accordance with professional ethics, including the duty to act impartially with a view to facilitating justice. 3.9 When law enforcement officials deprive an individual of liberty, for instance by detaining that person or placing him or her in custody, they assume a greater responsibility to protect that individual’s rights, in particular the rights to life and to physical integrity. Where a person dies in custody, including as a result of the use of less-lethal weapons, there is a presumption of responsibility of the State, and the burden of proof rests upon the State to prove otherwise. In any event, a prompt, impartial, independent, effective and transparent investigation must be carried out by an independent body.42 3.10 Where an investigation into the use of force by law enforcement officials reveals evidence that a death or injury may have been caused unlawfully, the State should ensure that perpetrators are prosecuted through a judicial process and, if convicted, given appropriate punishment.43 Punishment for the unlawful use of force by law enforcement officials shall be effective, proportionate and dissuasive. Where domestic or international law or an administrative regulation is violated, retraining or requalification may be required in addition to any criminal law or disciplinary sanction or any civil law penalty that may be imposed on the law enforcement officials responsible. See generally the Minnesota Protocol on the Investigation of Potentially Unlawful Death (2016), OHCHR, Geneva, 2017. 42 Minnesota Protocol on the Investigation of Potentially Unlawful Death, para. 17. 43 Ibid., para. 8 (c). 41