HASSAN v. THE UNITED KINGDOM – JUDGMENT 27 evidence or pre-determined formulae for its assessment. It adopts the conclusions that are, in its view, supported by the free evaluation of all evidence, including such inferences as may flow from the facts and the parties’ submissions. According to its established case-law, proof may follow from the coexistence of sufficiently strong, clear and concordant inferences or of similar unrebutted presumptions of fact. Moreover, the level of persuasion necessary for reaching a particular conclusion and, in this connection, the distribution of the burden of proof, are intrinsically linked to the specificity of the facts, the nature of the allegation made and the Convention right at stake. The Court is also attentive to the seriousness that attaches to a ruling that a Contracting State has violated fundamental rights (see El Masri v. “the former Yugoslav Republic of Macedonia” [GC], no. 39630/09, § 151, ECHR 2012). 49. Furthermore, it is to be recalled that Convention proceedings do not in all cases lend themselves to a strict application of the principle affirmanti incumbit probatio (the principle, that is, that the burden of proof lies on the person making the allegation in question). The Court reiterates its case-law under Articles 2 and 3 of the Convention to the effect that where the events in issue lie within the exclusive knowledge of the authorities, as in the case of persons under their control in custody, strong presumptions of fact will arise in respect of injuries and death occurring during that detention. The burden of proof in such a case may be regarded as resting on the authorities to provide a satisfactory and convincing explanation. In the absence of such explanation the Court can draw inferences which may be unfavourable for the respondent Government. The Court has already found that these considerations apply to disappearances examined under Article 5 of the Convention, where, although it has not been proved that a person has been taken into custody by the authorities, it is possible to establish that he or she was officially summoned by the authorities, entered a place under their control and has not been seen since. In such circumstances, the onus is on the Government to provide a plausible and satisfactory explanation as to what happened on the premises and to show that the person concerned was not detained by the authorities, but left the premises without subsequently being deprived of his or her liberty. Furthermore, the Court reiterates that, again in the context of a complaint under Article 5 § 1 of the Convention, it has required proof in the form of concordant inferences before the burden of proof is shifted to the respondent Government (see El Masri, cited above, §§ 152-153). 50. It is not in dispute in the present case that the applicant’s brother was captured by United Kingdom forces on 23 April 2003, subsequently detained at Camp Bucca and that he died shortly before his body was found in Samara on 1 September 2003. The disagreement over the facts centres on two issues: first, whether Tarek Hassan was arrested and detained as a means of exerting pressure on the applicant to surrender himself and,