"We will never have investigated all the cases," said Jens Rommel, who has just taken over as leader of the Central Office for Investigating National-Socialist Crimes in the small town of Ludwigsburg, Baden-Württemberg.
He and his team hunt for evidence in archives all over the world in the hopes of achieving whatever justice is possible for victims of the Nazis and their descendants.
"We don't even know all of the crimes – and we absolutely don't know all of the perpetrators."
Rommel, a high-ranking state prosecutor, has been in charge in Ludwigsburg since early December.
Jens Rommel in the archives at Ludwigsburg. Photo: DPA
Earlier this year, the justice ministers of all the German states decided that the office should continue the work it has been doing since 1958.
No decision has yet been reached on when the investigators will wind up their work and turn the office into an archive and research centre.
But it is unlikely to be long after the passing away of the final surviving perpetrators, such as Oskar Gröning, the so-called 'Auschwitz bookkeeper' convicted of abetting 300,000 cases of murder earlier this year.
A trial date in 2016 has already been set for another 95-year-old former Auschwitz SS man after he was found fit to face the court.
"At some point, the trials will collectively fail" due to the lack of living defendants capable of standing trial, Rommel said.
He and his team, though, continue to fight for a broader legal definition of complicity in the crimes committed at death camps and elsewhere.
"An accomplice doesn't have to have made a concrete contribution to a specific act of murder; rather involvement in the overall system that was aimed at extermination is sufficient," Rommel said.
Whether they are successful will be determined in the Federal Court of Justice, which is soon to consider Gröning's appeal against his conviction.