38 CYPRUS v. TURKEY JUDGMENT an arguable claim that Greek-Cypriot persons who were detained by Turkish forces or their agents in 1974 disappeared thereafter. For the Commission, a breach of the Article 5 obligation had to be construed as a continuing violation, given that the Commission had already found in its 1983 report on application no. 8007/77 that no information had been provided by the respondent Government on the fate of missing Greek Cypriots who had disappeared in Turkish custody. The Commission stressed that there could be no limitation in time as regards the duty to investigate and inform, especially as it could not be ruled out that the detained persons who had disappeared might have been the victims of the most serious crimes, including war crimes or crimes against humanity. 146. The Commission, on the other hand, found there had been no violation of Article 5 by virtue of actual detention of Greek-Cypriot missing persons. It noted in this regard that there was no evidence to support the assumption that during the period under consideration any missing Greek Cypriots were still detained by the Turkish or Turkish-Cypriot authorities. 147. The Court stresses at the outset that the unacknowledged detention of an individual is a complete negation of the guarantees of liberty and security of the person contained in Article 5 of the Convention and a most grave violation of that Article. Having assumed control over a given individual, it is incumbent on the authorities to account for his or her whereabouts. It is for this reason that Article 5 must be seen as requiring the authorities to take effective measures to safeguard against the risk of disappearance and to conduct a prompt and effective investigation into an arguable claim that a person has been taken into custody and has not been seen since (see the Kurt v. Turkey judgment of 25 May 1998, Reports 1998III, p. 1185, § 124). 148. The Court refers to the irrefutable evidence that Greek Cypriots were held by Turkish or Turkish-Cypriot forces. There is no indication of any records having been kept of either the identities of those detained or the dates or location of their detention. From a humanitarian point of view, this failing cannot be excused with reference either to the fighting which took place at the relevant time or to the overall confused and tense state of affairs. Seen in terms of Article 5 of the Convention, the absence of such information has made it impossible to allay the concerns of the relatives of the missing persons about the latter's fate. Notwithstanding the impossibility of naming those who were taken into custody, the respondent State should have made other inquiries with a view to accounting for the disappearances. As noted earlier, there has been no official reaction to new evidence that Greek-Cypriot missing persons were taken into Turkish custody (see paragraph 134 above). 149. The Court has addressed this allegation from the angle of the procedural requirements of Article 5 of the Convention and the obligations devolving on the respondent State as a Contracting Party to the Convention.