From the article:
The court said in a statement before the trial that the defendant allegedly "aided and abetted those in charge of the camp in the systematic killing of those imprisoned there between June 1943 and April 1945 in her function as a stenographer and typist in the camp commandant’s office."
Despite her advanced age, the German woman was to be tried in juvenile court because she was under 21 at the time of the alleged crimes. German media identified her as Irmgard Furchner.
...
The case against Furchner relies on German legal precedent established in cases over the past decade that anyone who helped Nazi death camps and concentration camps function can be prosecuted as an accessory to the murders committed there, even without evidence of participation in a specific crime.
People in the US who did not participate directly in a crime but in some way knowingly abetted the crime or the perps' escapes are routinely tried in the US as accessories, so this is hardly unprecedented. I have no problem with Furchner being prosecuted.
If convicted, as the old saying goes, her gray haired head should not go to the grave in peace, not with the magnitude of the crime in she played a part.