78 GIULIANI AND GAGGIO v. ITALY JUDGMENT investigation had to be entrusted to a police authority, the State could not be said to have lacked impartiality in any sense. Furthermore, the findings of the investigation and the reasons given for discontinuing the proceedings had provided no grounds for supposing that there had been any attempt at a cover-up. 297. All the experts appointed by the public prosecutor's office had been civilians, with the exception of the second ballistics expert, who was a police officer (see paragraph 55 above). At the time of Mr Romanini's appointment the prosecuting authorities had been unaware that he had expressed the view that M.P. had acted in self-defence (see paragraph 56 above). In the Government's submission, the aim of Mr Romanini's article had been simply to propound a political theory based on a comparison between the incident in question and an earlier tragedy in Naples. The fact that he had written the article did not render Mr Romanini unfit to fulfil his mandate in an objective and impartial manner, as his task had not consisted in examining whether the facts supported the hypothesis that M.P. had acted in self-defence. The panel of experts had been asked in particular to give its views on the trajectory of the bullet. Moreover, Mr Romanini's role had been confined to conducting test shootings in the presence of the other experts, the applicants and the latter's experts. That “purely technical and essentially physical” procedure had not afforded scope for preconceived judgments liable to influence the outcome of the investigation. The Government further observed that the applicants had not raised any objections to Mr Romanini's appointment. B. The Court's assessment 1. General principles 298. Having regard to their fundamental character, Articles 2 and 3 of the Convention contain a procedural obligation to carry out an effective investigation into alleged breaches of the substantive limb of these provisions (see Ergi v. Turkey, 28 July 1998, § 82, Reports 1998-IV; Assenov and Others v. Bulgaria, 28 October 1998, §§ 101-106, Reports 1998-VIII; and Mastromatteo, cited above, § 89). A general legal prohibition of arbitrary killing by the agents of the State would be ineffective, in practice, if there existed no procedure for reviewing the lawfulness of the use of lethal force by State authorities. The obligation to protect the right to life under this provision, read in conjunction with the State's general duty under Article 1 of the Convention to “secure to everyone within [its] jurisdiction the rights and freedoms defined in [the] Convention”, requires by implication that there should be some form of effective official investigation when individuals have been killed as a result of the use of force by, inter alios, agents of the State (see McCann and