The interpreter, speaking on condition of anonymity, said he was wounded when a three-vehicle patrol was attacked with explosives, rocket-propelled grenades and gunfire in northeastern Bamyan province in August 2010.
He was reportedly working with New Zealand military forces assigned to Provincial Reconstruction Teams.
New Zealand investigative journalist Jon Stephenson told Radio New Zealand, "(The interpreter) left the PRT because he was disappointed they were not giving him the medical treatment that he needed in terms of posttraumatic stress disorder, so he's gone to Turkey to seek medical treatment then fled to Germany because he feared for his life."
Vowing that no interpreter "would be left behind," on Tuesday New Zealand's military extended resettlement packages to 10 more interpreters after earlier offering it to 23 interpreters employed by the PRT.
About 116 people, including Afghan interpreters and their dependents, have been declared eligible for resettlement in New Zealand.
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