BERLIN — German prosecutors said Wednesday that they have dropped an investigation of a 95-year-old former Nazi concentration camp guard after he declined to be questioned following his deportation from the United States.

Friedrich Karl Berger arrived in his native Germany in February after being ordered deported by a court in Memphis last year.

Prosecutors in the northern town of Celle said at the time that he told German police he would be willing in principle to be questioned by investigators with a lawyer present. But they said Wednesday that Berger’s attorney later said his client was “not available” for questioning as a suspect.

They decided to close their investigation “after exhausting all evidence.”