BERLIN — German prosecutors have shelved their Nazi war crimes investigation of a retired Minnesota carpenter whom The Associated Press exposed as a former commander in an SS-led unit, saying Friday that the 96-year-old is not fit for trial.

Munich prosecutor Peter Preuss told The AP that Michael Karkoc’s attorney had refused to allow him to be examined by a medical expert from Germany, and that his office’s decision was based on “comprehensive medical documentation” from doctors at the geriatric hospital in the U.S. where he is being treated.

He said doctors there had provided prosecutors with a comprehensive assessment of Karkoc’s health over the past year, which was evaluated by a medical expert in Germany.

“There are no doubts about the authenticity of the documentation of his treatment,” said Preuss, who declined to provide specifics about Karkoc’s health on privacy grounds.

The German investigation began after AP published a story in 2013 establishing that Karkoc commanded a unit in the SS-led Ukrainian Self Defense Legion accused of burning villages filled with women and children, then lied to American immigration officials to get into the United States a few years after World War II.

A second report uncovered evidence that Karkoc himself ordered his men in 1944 to attack a Polish village in which dozens of civilians were killed, contradicting statements from his family that he was never at the scene.

Karkoc’s family, who live in Minneapolis, have denied he was involved in any war crimes.

Karkoc’s son and family spokesman, Andriy Karkos, said by phone Friday that he planned a statement later in the day about the case and that he looked forward to clearing his father’s name, but declined further comment.

The U.S. Department of Justice has refused to say whether it has ever investigated Karkoc, citing its policy of neither confirming nor denying investigations.

Department of Justice spokesman Peter Carr said Friday he also could not comment on whether his office would now pursue deportation proceedings against Karkoc.

“As we have said previously, we are aware of the allegations but will decline further comment at this time,” he said in an email.