The main motives were: revenge for those murdered, especially those murdered on ethnic grounds in the Holocaust (principally among Jews, Poles, and Russians); a desire after the war to see those responsible face justice, and be categorised as criminals by a court of law (See Nuremberg Trials); a means of ensuring that criminal acts done were brought to light and placed on the official record, with evidence, so that they could never be disproven (some of the acts being so unthinkable that denial was plausible); widespread sense that genocide of whole communities and cultures on such a scale was intolerable and must not be left unprosecuted even despite the inadequacy of existing laws; and fear that a "Nazi underground" of some kind existed, such as the mythical ODESSA, which could allow the enemy to somehow regroup for their proclaimed Fourth Reich.
Others were subject to after-war spontaneous retaliation in occupied countries, which in some areas led to "witch hunts" for those suspected of having been collaborators, in which vigilantism and summary justice were common.
After a first period of spontaneous pursuit, provisional governments took the matter into their own hands and brought suspected criminals to court.
The Nuremberg Trial in Germany judged only the highest German Nazi authorities, and each country prosecuted and sentenced their own collaborationists.
Nazi support and escape organisations were infiltrated; the most famous was the ODESSA network, its various "ratlines" and those believed to have aided and abetted them.
In March 1998, Ustasha Dinko Šakić, the former commandant of Jasenovac concentration camp (nicknamed the "Auschwitz of the Balkans"), was interviewed on national television in Argentina, where he had lived for over 50 years.
He was accused of the murder of Peter Balazs, an 18-year-old Jewish man, in Budapest in November 1944, while serving in the Hungarian Army.
One Belgian to be sentenced to execution was Pierre Daye; however, he was one of the first Nazi collaborators to escape Europe, and unusually by plane.
Now secure in his freedom, Pierre Daye resumed his writing activities, becoming the editor of an official Perónist review.
[2][6] Henri de Man was one of the leading Belgian socialist theoreticians of his period, who collaborated with Nazi Germany during World War II.
Immediately after the liberation of Czechoslovakia by Soviet and American armies, in an atmosphere of chaos, wild chases began.
In some places were conducted, by organised groups of self-styled partisans, violence which resembled what is today known as ethnic cleansing.
Other forms included legal action, undertaken by the state administration, after the war, until the regular Czech parliament was established.
By decree 12/1945 Sb., farm property of German and Hungarian nationals or citizens was confiscated, unless they could prove active resistance against Nazism.
Most problematic was the law 115/1946, concerning resistance to the Nazi regime, which shifted limit of immunity to the year 1946, effectively amnestying all crimes, acts of individual revenge and atrocities against Germans and Hungarians long after the war.
The infamous Karl Linnas, who had been sentenced to death in absentia, was finally deported by the United States in 1987, and died in a prison hospital shortly after.
However, the Provisional Government of the French Republic (GPRF, 1944–46) quickly reestablished order and brought collaborators before the courts.
Between 1944 and 1951, official courts in France sentenced 6,763 people to death (3,910 in absentia) for treason and other offences, and 791 executions were actually carried out.
For example, Maurice Papon, who would be convicted in the 1990s for his role in the Vichy collaborationist government, was in the position of giving orders for the Paris massacre of 1961 as the head of the Parisian police.
Many war criminals were judged only in the 1980s, including Paul Touvier, Klaus Barbie, Maurice Papon and his deputy Jean Leguay.
The second collaborationist leader, Konstantinos Logothetopoulos, who had fled to Germany after the Wehrmacht's withdrawal, was caught by the US military and was condemned to life imprisonment.
Ioannis Rallis, the third collaborationist prime minister, was tried on a treason charge; the court sentenced him to life imprisonment.
Indeed, in many cases the same people who had collaborated with the Germans and staffed the post-war security establishment persecuted leftist former Resistance members.
Vidkun Quisling, the war time Norwegian "Minister President", and, among others, Nasjonal Samling leaders Albert Viljam Hagelin and Ragnar Skancke, were convicted and executed by firing squad.
Both at the time and later these sentences were the subject of some debate, since the decision to reintroduce capital punishment to the Norwegian legal system for the post war trials was based on clauses in military law.
The decision was made by the exiled Norwegian government in London in 1944, later to be debated three times in the Parliament during the trials, and to be confirmed by the Supreme Court.
In general, after a short trial, if they were not executed, Nazi collaborators were imprisoned in Gulag forced labour camps.
Yugoslav collaborators were handed over to Josip Broz Tito's forces in the Bleiburg repatriations, with many being imprisoned while some killed as a result.
On 1 April 1999, Anthony Sawoniuk was sentenced to life in prison after being found guilty of murdering 18 Jews in Britain's first Nazi war crimes trial.
Sawoniuk had led "search-and-kill" police squads to hunt down Jews trying to escape after nearly 3,000 were massacred at Domachevo in Nazi-occupied Belarus during September 1942.