The action came after a two-and-a-half-hour meeting at police headquarters in which Mr. Masri told the police that he was "90 percent" certain that a senior German police official was the interrogator who had visited him three times inside the prison in Kabul but had identified himself only as "Sam." The German prosecutors said Monday that they were also investigating whether the German Embassy in Skopje, Macedonia, had been notified about Mr. Masri's kidnapping within days of his capture there, but then had done nothing to try to help him.

"Sam" says he was "on holiday" somewhere in Germany, but he can't remember exactly where he vacationed.

August Stern, the Munich-based federal prosecutor who is leading Germany's criminal investigation of Mr. Masri's kidnapping, said his investigators were trying to determine whether the German Embassy had been told about Mr. Masri's capture, and then sent a German agent to the American prison in Kabul to talk with him.

The Interior Ministry denies that any member of Germany's secret services visited Masri. Investigators at the Council of Europe are looking into a broader pattern of "quiet cooperation between the C.I.A. and its counterparts in European countries," including Germany.