In an upmarket suburb of Buenos Aires, 6,000 miles from the racially supremacist Nazi ideology from which it derived, lay a device used to measure head size. Contained in a velvet-lined box, it will soon go on public display in Argentina as part of an exhibition of dozens of Nazi relics seized by police from an art collector’s home.

The case has ignited speculation over who has cashed in by selling such items to obviously eager buyers. All were claimed by the collector to be mere reproductions, but have since been confirmed as original Nazi-era memorabilia, valued at £20 million. Suspicion has fallen on the families of the thousands of high-ranking Nazis who fled Hitler’s defeated Third Reich to South America at the end of the Second World War and escaped justice.

Walter Rauff, an SS colonel who developed mobile gas chambers that killed at least 100,000 people, died from a heart attack in Chile in 1984 and was honoured with a funeral in a prestigious cemetery at a ceremony attended by several notorious Nazis. Eduard Roschmann, the so-called Butcher of Riga, died in Paraguay in 1977. Gustav Wagner, an SS officer known as The Beast, committed suicide in Brazil in 1980 despite the country’s Supreme Court refusing to extradite him to Germany because of inaccuracies in the paperwork.

A Nazi rally in Buenos Aires, 1938.

They were among an estimated 9,000 former Nazi party members and SS officers who settled into life in Argentina, or went elsewhere on the continent. Any direct survivors today would be well into their 90s, but many had families who have stayed on, with the potential to sell their trophies or memorabilia.

They were among an estimated 9,000 former Nazi party members and SS officers who settled into life in Argentina.

“Almost every week I get a call from someone here in Argentina and the wider region who says they’ve seen, or lived at one stage, next door to a Nazi,” Ariel Gelblung, the Latin America representative at the Simon Wiesenthal Center, told The Times.

Those who settled in Argentina included death-camp commanders and Auschwitz doctors. “Argentina provided extensive assistance to escaping Nazi war criminals,” Uki Goñi, an author and expert on the Nazis, said.

The area of Buenos Aires in which the Nazi hoard was found was home to some of the most senior Nazis who managed to escape the immediate dragnet after the war. Adolf Eichmann, a mastermind of the Holocaust, lived a few streets away from where the skull-measuring instrument was found.

Those who settled in Argentina included death-camp commanders and Auschwitz doctors.

He arrived in the city using the name Riccardo Klement. He spent years with his wife and their four sons in the leafy neighbourhood of Béccar, which boasts a yacht club and a scenic railway line. He worked at a Mercedes Benz factory, with a brief spell as a rabbit farmer.

The newly uncovered artefacts include a bust of Hitler, an eagle statue and harmonicas bearing swastikas. They had been hidden behind a bookshelf in the collector’s house in Béccar, on a road that runs parallel to where the Eichmann family lived before he was captured by Mossad agents in 1960. The house was later demolished.

Adolf Eichmann in a glass prisoner’s booth in Israel during his trial for war crimes.

Eichmann was executed in Israel two years later but was survived by two of his sons. The youngest, Ricardo, 63, a professor of archaeology in Berlin, told The Times that he denounced his father, saying his execution was justified, but declined to further discuss his family.

Josef Mengele, the Nazi doctor known as the Angel of Death for his gruesome experiments on Auschwitz prisoners, lived for years in the area before he drowned in Brazil in 1979.

A rare magnifying glass, and a photo of Hitler holding it, are the items in the collection most closely associated with the Führer. Some pieces have been donated to the Buenos Aires Holocaust memorial museum, where Jonathan Karszenbaum, its director, believes it is a clear indication that the original proprietor was in the Nazi “hierarchy”. The other objects have been seized by the justice ministry as police try to find out who they originally belonged to.

A rare magnifying glass, and a photo of Hitler holding it.

The collector, Carlos Olivares, 57, who runs an antiques shop in the upmarket district of Olivos, is being prosecuted for violating cultural heritage protection laws and trying to sell “discriminatory goods”. He faces up to three years in prison if convicted but says he purchased the items more than 20 years ago in the city, believing them to be copies.

German W.W. II objects seized in Buenos Aires.

Mr Karszenbaum said another large box of Nazi paraphernalia was found five months ago in the region of La Boca in Buenos Aires.

Patricia Bullrich, the security minister, said the scale of the latest find reflected the many Nazi sympathisers in Argentina in the aftermath of the war. “There is no one who sells [objects such as these] just because. They sell them because there’s a historic network of people in Argentina who have created a demand for this part of history,” she said.

“There’s a historic network of people in Argentina who have created a demand for this part of history.”

Argentina was the last country in the Americas to declare war on Germany, in March 1945. Thousands of German immigrants settled in the country under Juan Perón, president of Argentina from 1946 to 1955. Many brought wealth and military expertise. Perón was drawn to the ideologies of Benito Mussolini and Hitler while serving as a military attaché in Italy during the early years of the war. He set out to recruit Nazis with technical skills that he believed could help his country to prosper.

Archives show that 10,000 blank Argentine passports were sold to Odessa, the organisation set up to protect former SS officers in the event of defeat, and which eventually helped them to avoid prosecution for war crimes. Outside Argentina, fascist-style military leaderships that developed in Brazil, Chile and Paraguay also provided safe havens for former Nazis.

“Few were brought to trial or have undergone recent investigation,” Dr Gelblung said. One elderly suspect died halfway through a court hearing in Argentina a few years ago. Little attention, however, has been given to his surviving relatives.