44 GÄFGEN v. GERMANY JUDGMENT of the Convention. As regards the way in which the impugned evidence had been obtained, they contested that the applicant had had to walk without shoes or had been subjected to further threats either in Birstein or on the return journey. 155. The Government accepted that the Regional Court had decided at the outset of the trial that the impugned items of evidence found in Birstein would be admitted as evidence at the trial. Nevertheless, the applicant had confirmed before the domestic courts that he had volunteered his confession at the trial out of remorse and because he wanted to take responsibility for his crime, even though he could also have remained silent or could have lied to the court. He might have changed his defence strategy in the hope that he would receive a more lenient sentence, but this decision had not been related to the use of the impugned items of evidence. It was not correct that the applicant had had no choice but to confess at the trial because, as the trial court had confirmed, it was possible that he might not have been found guilty of murder had he not confessed anew. Following a qualified instruction by the trial court, he had confessed, on the second day of his trial, and it was clear from this confession that he had killed J. intentionally. The difference between the first trial confession and the later one was comparatively minor in that the former had not included an admission that the death of J. had been part of his plan from the outset. This additional admission was not a necessary element to prove murder. 156. The Government underlined that the applicant’s conviction had been based on the confession he had volunteered at his trial. The items of evidence secured after the journey to Birstein, such as J.’s corpse and the autopsy report thereon and the tyre tracks from the applicant’s car at the pond, had been of an accessory nature only and had been used merely to test the veracity of the applicant’s confession at the trial. This was clearly stated in the reasoning of the Regional Court’s judgment convicting the applicant. 157. The Government noted that Article 6 of the Convention did not lay down any rules on the admissibility of evidence, as such, which was primarily a matter for regulation under national law. They underlined their obligation under the Convention to apply the criminal law against a murderer. The public interest in having the murderer of an abducted child convicted was of very serious weight. The Government further argued that the case-law of the United States Supreme Court, which went furthest in prohibiting the use of the “fruit of the poisonous tree”, needed careful analysis. In the leading case of Nix v. Williams (decision of 11 June 1984, 467 US 431; see paragraph 73 above), for instance, that court had held that a body found after an improper investigation could be admitted into evidence in circumstances where it would have been found in any event. It was likely in the present case that J.’s corpse, hidden at a place which the applicant had previously visited, would have been found sooner or later.