He actually sealed his own fate in the early 1950s with a letter he wrote to his half-brother Mikolai in Poland, who he had not seen since World War II.

At the time, all mail from the West was vetted by the KGB, which already had Sawoniuk on its records of possible war criminals who had escaped abroad.

As the Soviet Union began to break down in the mid-1980s the list was submitted to British authorities. However, Sawoniuk's name had been spelled wrong. He was also known by his first name, Andrusha.

Sawoniuk as a soldier in World War II

Only in 1993, when the names were reviewed, did it emerge that one of the men on the KGB records had moved to Britain.

By then, Sawoniuk had retired after an unremarkable and routine 25 years working for British Rail and living in London.

He had slipped into Britain in the middle of 1945, under the guise of a Polish patriot who had fought Hitler alongside the Allies throughout the six-year war.

Instead, he had played a bloody first-hand role in the Nazi's Holocaust which left six million Jewish people dead across Europe.

Helped by Jews

Sawoniuk was born on 7 March 1921 in a remote area of Europe, that is Domachevo, Belarus. Fatherless, he may have starved in the harsh climate but for, ironically, the generosity of local wealthy Jewish families.

But when the Germans swept into the town in 1941, he quickly took up with the invading force. They gave the penniless, resentful youth the power of life or death over his Jewish former benefactors.

The house in Domachevo that he stole from Jews

A 20-year-old Sawoniuk joined the Nazi's police force which was geared towards pursuing the policies of suppression and genocide of Jews locally. He displayed enthusiasm in dispensing his tasks of rounding up and murdering Jews trying to escape the massacre.

An old school friend, Fedor Zan, watched him change. "Nobody could stand him. He had an animal attitude to people," said Mr Zan.

In July 1944 Sawoniuk left Domachevo to serve in a Belarussian Waffen SS Unit in Italy.

Then in December, with the tide of the war turning against the Germans, Sawoniuk went missing while serving in the crack SS Border Regiment. He had left to join Polish troops fighting alongside the British Army.

No questions asked

The Polish forces had been so chronically depleted by the war that they did not ask many questions of their newest recruits.

In mid-1945 he arrived in Britain, staying in camps in Scotland until well into 1946, when he was discharged.

The Polish Resettlement Corps was responsible for helping 110,000 Polish servicemen and their families who were given the right to stay in Britain.

Screening was minimal, with the authorities tending to assume that anyone who had served with the Allies was not a Nazi.

Questions were raised in Parliament, but there was little enthusiasm among MPs to seek out war criminals.

Moved around Britain

After leaving Scotland, Sawoniuk moved first to Brighton, then Bognor Regis, before finally settling in London in 1954 with his Irish wife, Anastasia.

For the next seven years he worked for the building department at St Francis's Hospital, Dulwich. He joined British Rail in 1961 and worked for them for the next 25 years.

Over the years, he absorbed the British way of life, shopping at Co-op and Marks and Spencer, and even adopting cockney in a fractured accent.

But all the while he was hiding a dark history. Sawoniuk had successfully cut himself off from his past. His half-brother had escaped soon after the invasion of Belarus, after realising what they were doing. He now lives peacefully in old age in Poland.

'Sadistic fervour'

But Sawoniuk had plundered from the Jews, even having one of their houses rebuilt for himself on his chosen site in the village. It still stands there today.

He carried out his police duties with sadistic fervour. Once, he discovered a young Jewish woman trying to smuggle a few potatoes into the ghetto and beat her savagely and put her into detention.

During the Nazi occupation, Sawoniuk married a Russian midwife, Anna Maslova. She later died during a partisan attack on the police station in Domachevo in 1943.

Marriaged several times

According to authorities, he married a second wife, Nina, in 1944. While pregnant, she fled with him from the Russian advance. Sawoniuk later denied she was his wife.

After the war he married once again - this time a Dutch woman, Christine Van Gent. They later divorced and Anastasia became his last wife in 1958. The couple had a son in 1961 and the marriage broke up within months.

Anastasia died shortly before Sawoniuk was questioned by the War Crimes Unit.

Neighbours on his Bermondsey estate were shocked at Sawoniuk's arrest in 1996. One, Marion Henry, 63, who had known him 20 years, called him "nice" and "charming".