Prosecutors in Germany have reopened hundreds of investigations of former Nazi death camp guards and others who might now be charged under a precedent set by the conviction of John Demjanjuk, a guard at Sobibor camp in Poland in 1943.

Given the advanced age of the suspects – the youngest is in his 80s – the head of the German prosecutors' office dedicated to investigating Nazi war crimes said authorities would not wait for the Demjanjuk appeal process to finish. "We don't want to wait too long, so we've already begun our investigations," Kurt Schrimm said.

The Simon Wiesenthal Centre's chief Nazi-hunter, Efraim Zuroff, said he would launch a campaign in the next two months – a successor to his Operation Last Chance – to track down the remaining war criminals.

He added that the Demjanjuk conviction had opened the door to prosecutions that were never thought possible. "It could be a very interesting final chapter," he said by telephone from Jerusalem. "This has tremendous implications, even at this late date."

Demjanjuk, now 91, was deported from the US to Germany in 2009 to stand trial. He was convicted in May of 28,060 counts of accessory to murder for serving as a guard at the Sobibor death camp. It was the first time prosecutors were able to convict someone in a Nazi-era case without direct evidence that the suspect participated in a specific killing. He has appealed against his conviction.

In bringing Demjanjuk to trial, Munich prosecutors argued that if they could prove he was a guard at a camp like Sobibor, which had been established for the sole purpose of extermination, it would be enough to convict him of being an accessory to murder.

After 18 months of testimony a Munich court agreed and found Demjanjuk guilty, sentencing him to five years in prison. Demjanjuk, a retired car worker who denies having served as a guard, is currently free and living in southern Germany as he waits for his appeal to be heard.

Schrimm said his office was poring over its files to see if others fit into the same category as Demjanjuk. He could not give an exact figure, but said there were probably "less than 1,000" possible suspects living in Germany and elsewhere who could face prosecution. "We have to check everything – from the people who we were aware of in camps like Sobibor … or also in the Einsatzgruppen," he said, referring to the death squads responsible for mass killings, particularly early in the war before the camps were established.

It has not yet been tested in court whether the Demjanjuk precedent could be extended to guards of Nazi camps where thousands died but whose sole purpose was not necessarily murder.

Murder and related offences are the only charges that are not subject to a statute of limitations in Germany. Even the narrowest scenario – investigating the guards of the four death camps: Belzec, Chelmno, Sobibor and Treblinka – plus those involved in the Einsatzgruppen could lead to scores of prosecutions, Zuroff said.

"We're talking about an estimated 4,000 people," he said. "Even if only 2% of those people are alive, we're talking 80 people – and let's assume half of them are not medically fit to be brought to justice – that leaves us with 40 people, so there is incredible potential."

Immediately after the war senior Nazis such as Hermann Göring were convicted at war-crimes trials run by the allied powers, while investigations of lower-ranking officials fell to German courts. But there was little political will to aggressively pursue the prosecutions, and many of the trials ended with short sentences or the acquittal of suspects in greater positions of responsibility than Demjanjuk allegedly had.

For example, Karl Streibel, the commandant of the SS camp Trawniki where Demjanjuk allegedly was trained, was tried in Hamburg but acquitted in 1976 after judges ruled it had not been proved that he knew what the guards being trained would be used for. But the current generation of prosecutors and judges in Germany has shown a willingness to pursue even the lower ranks, something applauded by Zuroff.

"Our goal is to bring as many people to justice as possible," Zuroff said. "They shouldn't be let off if they're less than Mengele, less than Himmler … in a tragedy of this scope their escaping justice should not in any way mean that people of a lesser level would be ignored."

Working in favour of the new investigators is the fact that most suspects would probably have lived openly and under their own names for decades, believing they had no prosecutions to fear. Those who are harder to locate will be the focus of the Wiesenthal centre's new appeal, which Zuroff said would include unspecified reward money for information that helps uncover a suspect.

However, Schrimm said it makes sense to try to bring new cases to trial once the Demjanjuk case is through the appeals process, rather than expend the resources needed to charge a suspect only to have the case thrown out if Demjanjuk wins. "The suspects are old, that's why we're preparing everything now so that as soon as there is a final decision, we can move immediately with charges," he said.

Zuroff said he hoped the appeal would be fast-tracked so new charges could be filed. "This is a test for the German judicial system to see if they can expedite this in an appropriate manner to enable these cases to go forward," he added.

guardian.co.uk