Adolf Eichmann, Klaus Barbie, Erich Priebke and Maurice Papon are some of the infamous offenders who have been tracked down and brought to justice.

Alois Brunner, Adolf Eichmann's right-hand-man, who was accused of sending 130,000 Jews to death camps, is one of the last senior Nazi officers still believed to be at large. He is thought to be living in Syria.

Tenacious: Simon Wiesenthal

Nazi Foreign Minister Joachim von Ribbentrop was among those executed at the end of the war, while Hermann Goering committed suicide just hours before he was due to mount the hangman's gallows in October 1946.

But a search headed by dedicated Nazi-hunters like Simon Wiesenthal continued for the leading perpetrators of war crimes.

Their most startling success was when Israeli secret services snatched Adolf Eichmann, one of the architects of the Holocaust, from a street in a suburb of Buenos Aires, Argentina, where he lived in obscurity with his family.

Eichmann, who orchestrated the execution of six million Jews and supervised the transportation of prisoners to concentration camps, was tried in Israel, convicted and hanged in May 1962.

Mengele: Escaped conviction

Josef Mengele, the Auschwitz 'Angel of Death' also escaped to Argentina - but he avoided being brought to justice.

American authorities admitted that they released Mengele, who performed hideous medical experiments on concentration camp prisoners, because they never realised who he was. He did not have the customary tattoo of SS officers.

Mengele, who determined who would be sent to the gas chambers and was held responsible for 400,000 deaths, fled to South America. He died in Brazil in 1969, aged 67.

Condemned to death

Klaus Barbie escaped justice for nearly 40 years, assisted by American intelligence officers who employed him as the battleground shifted to the Cold War.

Barbie: Condemned to death for killing thousands

He was finally returned to France from Bolivia in 1983 to stand trial for crimes against humanity. He was jailed for life and died in 1991, aged 77.

In the 1950s, he was condemned to death in his absence by two French courts for his part in more than 4,000 killings and the deportation of more than 7,000 Jews to the concentration camps.

The 1990s were punctuated with a mixture of successes and failures as the investigators continued to press for successful convictions.

Priebke: Life for Rome massacre

In Italy, former SS Captain Erich Priebke was given a life sentence in 1998 for his role in the massacre of 335 civilians in caves outside Rome in 1944.