An initial probe was first reported at the weekend into some 50 suspected former Auschwitz guards, now aged around 90, for complicity in murder, by the Central Office for the Investigation of National Socialist Crimes.
"We are also looking at the other extermination camps and the task forces," as the SS death squads were known, said Kurt Schrimm, the head of the investigative office based in the southwestern city of Ludwigsburg.
The scope of the pursuit of former Nazi war criminals has broadened since Germany's 2011 conviction of Ukraine-born John Demjanjuk, a former guard at the Sobibor death camp in occupied Poland who died last year.
The court in that case deemed that any function at a concentration camp amounted to accessory to murder. Demjanjuk was sentenced to five years in prison for complicity in the murders of more than 20,000 people.
Nazi Germany's biggest death camp was Auschwitz-Birkenau in occupied Poland where more than one million people were murdered between 1942 and 1945.
Schrimm told news agency AFP on Monday that it was now unlikely that any more surviving Auschwitz guards would be found, aside from the 50 for whom the office had collated the names, addresses and birth dates.
"First we need to establish against which of them a prosecution is still legally possible," said Schrimm, as those who had been tried in the past for serving in Auschwitz could not face court a second time.
For those among the 50 who had never faced justice before, the investigators were now trying "to reconstruct who did what where and when," he said, stressing that the probe was still in its early phase.
"At the moment we only know their names, addresses and dates of birth," he said, and no contact had been established yet with any of the suspects.
In cases where a prosecution is deemed possible, the office would send the necessary files to regional prosecutors in the states where the suspects live so that criminal proceedings could then be launched, Schrimm said.
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If any of the suspects live abroad, a German federal court would decide which regional prosecution service should pursue the case.
The Central Office for the Investigation of National Socialist Crimes, established in 1958 and funded by Germany's 16 states, has so far conducted 7,485 investigations against suspected former Nazi war criminals.