24 BOUYID v. BELGIUM JUDGMENT of the person concerned (see, among other authorities, Chahal v. the United Kingdom, 15 November 1996, § 79, Reports of Judgments and Decisions 1996-V, and Labita, Gäfgen and El-Masri, all cited above; see also Georgia v. Russia (I) [GC], no. 13255/07, § 192, ECHR 2014, and Svinarenko and Slyadnev v. Russia [GC], nos. 32541/08 and 43441/08, § 113, ECHR 2014). 82. Allegations of ill-treatment contrary to Article 3 must be supported by appropriate evidence. To assess this evidence, the Court adopts the standard of proof “beyond reasonable doubt” but adds that such proof may follow from the coexistence of sufficiently strong, clear and concordant inferences or of similar unrebutted presumptions of fact (see, among other authorities, Ireland v. the United Kingdom, 18 January 1978, § 161 in fine, Series A no. 25; Labita, cited above, § 121; Jalloh v. Germany [GC], no. 54810/00, § 67, ECHR 2006-IX; Ramirez Sanchez v. France [GC], no. 59450/00, § 117, ECHR 2006-IX; and Gäfgen, cited above, § 92). 83. On this latter point the Court has explained that where the events in issue lie wholly, or in large part, within the exclusive knowledge of the authorities, as in the case of persons within their control in custody, strong presumptions of fact will arise in respect of injuries occurring during such detention. The burden of proof is then on the Government to provide a satisfactory and convincing explanation by producing evidence establishing facts which cast doubt on the account of events given by the victim (see Salman, cited above, § 100; Rivas v. France, no. 59584/00, § 38, 1 April 2004; and also, among other authorities, Turan Cakir v. Belgium, no. 44256/06, § 54, 10 March 2009; Mete and Others v. Turkey, no. 294/08, § 112, 4 October 2011; Gäfgen, cited above, § 92; and El-Masri, cited above, § 152). In the absence of such explanation, the Court can draw inferences which may be unfavourable for the Government (see, among other authorities, El-Masri, cited above, § 152). That is justified by the fact that persons in custody are in a vulnerable position and the authorities are under a duty to protect them (see, among other authorities, Salman, cited above, § 99). 84. The Chamber found in the present case that the same principle held true in the context of an identity check in a police station (as in the case of the first applicant) or a mere interview on such premises (as in the case of the second applicant). The Grand Chamber agrees, emphasising that the principle set forth in paragraph 83 above applies to all cases in which a person is under the control of the police or a similar authority. 85. The Court also pointed out in the El-Masri judgment (cited above, § 155) that, although it recognised that it must be cautious in taking on the role of a first-instance tribunal of fact where this was not rendered unavoidable by the circumstances of a particular case (see McKerr v. the United Kingdom (dec.), no. 28883/95, 4 April 2000), it had to apply a “particularly thorough scrutiny” where allegations were made under Article 3 of the Convention (see, mutatis mutandis, Ribitsch v. Austria,