95. The Court has previously noted the fundamental importance of the guarantees contained in Article 5 to secure the right of individuals in a democracy to be free from arbitrary detention. It has also stated that unacknowledged detention is a complete negation of these guarantees and discloses a very grave violation of Article 5 (see v. Turkey, No. 25704/94, § 164, 27 February 2001, and Luluyev, cited above, § 122).
96. The Court has found it established that Ramzan Rasayev was apprehended by State servicemen on 25 December 2001 and has not been seen since. His detention was not acknowledged, was not logged in any custody records and there exists no official trace of his subsequent whereabouts or fate. In accordance with the Court's practice, this fact in itself must be considered a most serious failing, since it enables those responsible for an act of deprivation of liberty to conceal their involvement in a crime, to cover their tracks and to escape accountability for the fate of a detainee. Furthermore, the absence of detention records, noting such matters as the date, time and location of detention and the name of the detainee as well as the reasons for the detention and the name of the person effecting it, must be seen as incompatible with the very purpose of Article 5 of the Convention (see Orhan, cited above, § 371).
97. The Court further considers that the authorities should have been more alert to the need for a thorough and prompt investigation of the applicants' complaints that their family member had been detained and taken away in life-threatening circumstances. However, the Court's findings above in relation to Article 2 and, in particular, the conduct of the investigation leave no doubt that the authorities failed to take prompt and effective measures to safeguard them against the risk of disappearance.
98. In view of the foregoing, the Court finds that Ramzan Rasayev was held in unacknowledged detention without any of the safeguards contained in Article 5. This constitutes a particularly grave violation of the right to liberty and security enshrined in Article 5 of the Convention.