Furchner was sentenced to two years' probation at the end of 2022, as she was deemed to be involved in "cruel and malicious murders" of prisoners in the Nazi concentration camp Stutthof in occupied Poland.
A federal court rejected her request to have the verdict overturned in a final review.
Furchner was a secretary and handled correspondence from the camp between June 1943 and April 1945, under the leadership of camp commander Paul Werner Hoppe. Furchner's husband was an SS officer at the camp. Therefore, the court ruled, Furchner was well aware of what happened to the victims in the camp.
Before the first trial, which was held in a specially built tribunal at the nursing home where she lived, the then 97-year-old Furchner managed to escape. She was arrested by police on the run in Hamburg.
As Furchner was a teenager when the crime was committed, her case was tried in a juvenile court.
Furchner has maintained her innocence.
Around 65,000 people were killed in Stutthof near Gdansk in today's Poland, including Jewish prisoners, Polish resistance fighters, and Soviet prisoners of war.
