34 GÄFGEN v. GERMANY JUDGMENT applicant’s human dignity and the prohibition on subjecting prisoners to illtreatment (Article 1 and Article 104 § 1, second sentence, of the Basic Law) had been disregarded (see paragraph 42 above). In addition to that, in its judgment of 20 December 2004 convicting police officers D. and E., the Frankfurt am Main Regional Court found that such methods of investigation could not be justified as an act of necessity because “necessity” was not a defence to a violation of the absolute protection of human dignity under Article 1 of the Basic Law, which also lay at the heart of Article 3 of the Convention (see paragraph 48 above). In view of this, the Grand Chamber, which agrees with the findings of the Chamber in this respect, is satisfied that the domestic courts which were called upon to rule on this issue acknowledged expressly and in an unequivocal manner that the applicant’s interrogation had violated Article 3 of the Convention. 121. In assessing whether the national authorities further afforded the applicant appropriate and sufficient redress for the breach of Article 3, the Court must determine, in the first place, whether they carried out a thorough and effective investigation against those responsible in compliance with the requirements of its case-law. In doing so, the Court has previously taken into account several criteria. Firstly, important factors for an effective investigation, viewed as a gauge of the authorities’ determination to identify and prosecute those responsible, are its promptness (compare, inter alia, Selmouni, cited above, §§ 78-79; Nikolova and Velichkova, cited above, § 59; and Vladimir Romanov, cited above, §§ 85 et seq.) and its expedition (compare Mikheyev v. Russia, no. 77617/01, § 109, 26 January 2006, and Dedovskiy and Others v. Russia, no. 7178/03, § 89, 15 May 2008). Furthermore, the outcome of the investigations and of the ensuing criminal proceedings, including the sanction imposed as well as disciplinary measures taken, have been considered decisive. It is vital in ensuring that the deterrent effect of the judicial system in place and the significance of the role it is required to play in preventing violations of the prohibition of illtreatment are not undermined (compare Ali and Ayşe Duran v. Turkey, no. 42942/02, § 62, 8 April 2008; Çamdereli, cited above, § 38; and Nikolova and Velichkova, cited above, §§ 60 et seq.). 122. The Court notes in the present case that criminal investigations against police officers D. and E. were opened some three to four months after the applicant’s questioning on 1 October 2002 (see paragraph 23 above) and that the officers were convicted in a final judgment some two years and three months after that date. Even though the Court notes that the Frankfurt am Main Regional Court mitigated their sentence in view of, among many other factors, the long duration of the proceedings (see paragraph 50 above), it is prepared to accept that the investigation and the criminal proceedings were, nevertheless, sufficiently prompt and expeditious to meet the standards set by the Convention.