The 93-year-old man, identified as Bruno D, was charged with 5,230 counts of accessory to murder over his time as an SS guard at the Stutthof concentration camp from 1944 to 1945.
He was found guilty by the Hamburg juvenile court of aiding and abetting in the murder of at least 5,232 people. He faced a juvenile court because he was 17 years old at the time he served in Stutthof.
The defendant had previously admitted to being a guard at the camp, but told the court at the beginning of his trial that he had no choice at the time.
More than 40 co-plaintiffs from France, Israel, Poland and the United States testified against the former SS guard during the trial, which began in October.
Concluding just over 75 years after World War II ended in Europe, it will almost certainly be one of the last trials of a former Nazi.
It is estimated that around 65,000 people were murdered during the Holocaust in the Stutthof concentration camp, near the Polish city now called Gdansk.
Landmark trial
Bruno D. came to the attention of prosecutors during the landmark trial of former Sobibor SS guard John Demjanjuk. He was indicted in April 2019 and lives with his family in Hamburg.
This comes after a 95-year-old man, accused of being a guard at the same camp as Bruno D, was charged July 14 with war crimes during the Holocaust, the Wuppertal, Germany district court announced last week.
German prosecutors are investigating 14 other cases connected to the concentration camps of Buchenwald, Sachsenhausen, Mauthausen and Stutthof, according to the Central Office for the Investigation of Nazi Crimes.