By Clare Murphy
BBC News Online
Many are dead. The rest are old, weak, and often senile. But sought after.
Tell the authorities that you suspect your ageing neighbour is a Nazi criminal and you could be up for a cash prize.
Operation Last Chance - a scheme devised by the Nazi-hunting Simon Wiesenthal Center - aims to flush out the remaining Nazi criminals in Europe who have eluded justice before they die.
"We've basically got around five years before they've all gone, we reckon," says the operation's head, Dr Efraim Zuroff. "We've got to get the information now, or it will be too late."
Crossing the continent
The campaign, inevitably, is not without controversy, and has so far produced mixed results.
It was first rolled out in the Baltic states: Lithuania, Estonia and Latvia, just over a year ago, and then late last year in Austria, Poland and Romania. In the coming months, the project will be launched in Germany, Hungary, Belarus and Ukraine.
It takes the form of a media campaign - normally carried in newspapers, and offers potential informants a reward of $10,000 for any information which results in the conviction of a Nazi criminal.
In the Baltic states, dozens of tip-offs have been received. They are currently being investigated by the authorities, although it remains unclear whether any of them are concrete enough to make it to court - let alone result in a conviction.
German troops went into Austria in 1938
"Massacres occurred within the communities in the Baltics," says Dr Zuroff. "It wasn't behind closed doors in death camps - so people know. They know who was involved, and many are keen to help out. We hope the authorities prove as eager."
Romanians have also shown themselves keen to help out, Poles less so, while the Austrians, according to the Simon Wiesenthal Center, have been positively hostile to the project.
"In some ways this was only to be expected," says Dr Zuroff, who claims to have received dozens of anti-Semitic letters from the country. "Austria has never come to terms with its role in World War II."
Dealing with the past
There is anecdotal evidence to suggest that some Austrians find the notion of financial encouragement to tell tales on an elderly neighbour distasteful, while others see it as a waste of time.
"Although there is no time limit in war crimes cases, there are always going to be issues about whether someone is fit enough to stand trial, and people recognise that," says Dieter Kindermann, an analyst at Austria's Die Kronen Zeitung newspaper, which carried one of the Operation Last Chance advertisements.
Operation Last Chance
"But Austria and Austrians are very clear about the fact that those who committed atrocities should be brought to justice. I can believe the Simon Wiesenthal Center has received some horrendous letters, I just don't think that is representative of Austria as a whole. The country sees itself as both a victim and a perpetrator."
Austria was annexed to Germany during the Anschluss of 1938; how much support the Nazi regime actually enjoyed in the country has been a subject of vigorous debate, but in 1993 the then chancellor, Franz Vranitzky, said the country had been a willing ally of the Nazi regime.
Austria's last Nazi trial - involving a doctor accused of complicity in the deaths of several hundred handicapped children in a Vienna clinic - was called off in 2000 after the defendant, Heinrich Gross, was declared incapable of standing trial due to senility.
But there are ways of circumventing the problems posed by apparently infirm suspects. Lithuania for example passed a law four years ago which allowed the sick to be tried in absentia, represented by a lawyer.
Kazys Gimzauskas, then 93, was thus found guilty of collaborating with the Nazis in killing Jews in Lithuania, although he was not sentenced.
Old and deported
Gimzauskas had been deported to Lithuania from the US, which has had an active policy of stripping citizenship and expelling those it suspects of Nazi war crimes.
Earlier this month, US authorities deported 82-year-old Algimantas Dailide to Germany, 54 years after he fled Lithuania for the US. He is suspected of handing Jews over to the Nazis.
"It is a very sad case," said Mr Dailide's lawyer, Joseph McGinness. "The two of them are over there with very little money. His wife is ill, and he isn't doing well, either."
But Dr Zuroff has no intention of letting any fish, large or small, rest in peace.
"It's utterly retarded to feel sorry for these people just because they are old. They showed no mercy whatsoever."