At first glance, the mugshots appear to be a gallery of roguish grandfathers, but the octo- and nonagenarians are the 10 most-wanted fugitives of one of the most heinous regimes the world has ever seen. They are the last remaining Nazis, and the codename of the hunt to find them – Operation Last Chance – says it all

More than 60 years after the Nuremberg trials put the first of Hitler's henchmen in the dock, the Simon Wiesenthal Centre yesterday released its most wanted list of the remaining Nazi war criminals. The battle to bring them to justice is complicated by a mix of political apathy, legal wrangling, legendary powers of evasion and what Nazi-hunters term "misplaced sympathy" for the craggy-faced men in their twilight years.

"They are old, and the natural tendency is to be sympathetic toward people when they reach a certain age, but the passage of time in no way diminishes the guilt of the perpetrators," said Efraim Zuroff, the Jerusalem-based director of the Wiesenthal Centre. "If we were to put a chronological limit on prosecution, we would basically be saying you can get away with genocide."

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The top target is Aribert Heim, now 93. Jewish prisoners at Mauthausen concentration camp probably knew better him as "Doctor Death". The Austrian medic would inject petrol and an array of different poisons straight into the hearts of his so-called patients to see which killed them fastest. He once removed the tattooed flesh of a prisoner and turned it into soft furnishings for his commandant's flat.

An 18-year-old Jewish footballer and swimmer who was sent to Heim with an inflammation of the foot was knocked out, castrated and then decapitated. His head was boiled to remove the flesh and his skull was put on display. "[Heim] needed the head because of its perfect teeth," testified one hospital worker at the camp, according to an arrest warrant uncovered by the Associated Press news agency.

Although the hunt for the fugitives continues, the race is on to bring them to justice before they die. Conscious of the ticking clock, Mr Zuroff will launch a media blitz in South America this summer, airing adverts there for the first time which publicise the $485,000 (£245,000) reward offered for Heim's arrest.

Heim has been on the run since 1962 when, happily married and working as a gynaecologist in the West German town of Baden-Baden, he was tipped off that his arrest was imminent. Proof that he is still alive after all these years may be the €1m (£785,000) sitting in a Berlin bank account, which would probably have been claimed by his family if he were dead. The best guess now is that the doctor is in either in Chile, where his daughter lives, or Argentina – a favoured destination for fleeing Nazis, including the architect of the Holocaust, Adolf Eichmann, and another lover of ghoulish medical experiments, Josef Mengele.

It is only Heim whose whereabouts are unknown. For the other nine suspects, Mr Zuroff rattles off a string of house numbers and street names in cities around the world – from Klagenfurt in Austria to Perth, Australia. In these cases, the biggest problem is a lack of political will. John Demjanjuk, a Ukrainian emigré, was extradited from the US to Israel in 1986 and sentenced to death for allegedly being the Treblinka camp guard "Ivan the Terrible". But Israel's Supreme Court overturned the ruling and released him. He is now fighting deportation from America.

"Some countries don't have the guts or the courage to prosecute and punish," sighs Mr Zuroff. "Nazi war criminals are not serial killers. They are not likely to murder again and the governments basically know that in a few years they will pass away."

Take Sandor Kepiro, who is No 3 on the list. Now aged 93, he was among Hungarian officers alleged to have carried out a three-day massacre of more than 1,000 mostly Jewish people on the banks of the Danube in Serbia. He was convicted in 1944 but was pardoned and moved to Austria. In 1946, he was convicted again – in absentia – and decided to flee further afield, this time to Argentina.

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Half a century later, he slipped secretly back into his homeland after being assured he would not face punishment. But when he was discovered living in Budapest in 2006, there was a public outcry. No decision has been made on whether he will stand trial.

Hungary is one of nine countries to be given a "failing" grade in the Wiesenthal Centre's annual scorecard. Sweden is another; lambasted for its blanket refusal to investigate Nazi-era crimes, because of a statute of limitations which kicks in at 25 years for all acts of murder, including genocide.

Another is Australia; accused of being too slow in processing the extradition of most-wanted Nazi No 7, Charles Zentai.

"For three years, they let this guy play games in court," says Mr Zuroff. "When you are talking about three years for someone who is in his 80s, that is a long time and could, effectively, help him elude justice."

Mr Zentai, now 86 and living in a Perth suburb, is accused of beating an 18-year-old called Peter Balazs to death when he caught him riding a Budapest tram without wearing a yellow star to identify himself as a Jew. Mr Zentai denies the charges and has been fighting extradition since 2005. Last week, he lost a constitutional challenge against state magistrates ruling on his case. His family claims the incriminating witness testimony came from confessions beaten out of soldiers. They say that he stands little chance of a fair trial in Hungary, should extradition go ahead.

Mr Zentai's son, Ernie Steiner, said yesterday: "I know my father was never a Nazi, so why is a Nazi-hunter hunting my father? He was never involved in the Holocaust or the mistreatment of Jews. So this is a complete fabrication."

He dismissed the Most Wanted List as the theatrics of a bounty hunter, saying: "Of course there's a principle of justice but, when you've got the wrong bloke, you are persecuting an innocent man."

One who didn't get away

The case of the "Executioner of Bolzano" has been a triumph for Nazi hunters. Michael Seifert tortured his victims in the north Italian concentration camp using fire, broken bottles, clubs and ice-cold water.

After the war he moved to Canada, working in a Vancouver mill and raising his family. In 2000, he was convicted in absentia and sentenced to life imprisonment for murdering at least 18 people but it was two years before he was arrested by the Canadian police at Italy's request. He began a long fight against extradition, which ended in failure this February when, at the age of 83, he was finally deported to Rome to serve his sentence.

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