A decision to investigate 30 alleged former guards at Auschwitz was prompted by the case of Ukraine-born John Demjanjuk.
Demjanjuk was the first Nazi war criminal to be convicted in Germany without evidence of a specific crime or victim but purely on the grounds he had served as death camp guard.
He died last year, aged 91, while appealing against a five-year jail sentence for complicity in the murder of more than 28,000 Jews at the Sobibor camp in Poland.
More top news
Five-times major winner Maria Sharapova has pulled out of the US Open tennis championships due to a leg injury.
Police are hunting for a mother who has disappeared with her 10-week-old baby.
The president will restore Denali as the name of the USA's highest mountain, which has been known as Mount McKinley.