When US scientists put a man on the moon 50 years ago, they had a helping hand from Nazi scientists who were seen as war criminals and accused of mass murder.
Wernher von Braun was a rocket engineer who designed the V2 missile that killed thousands of people in Allied cities such as London during the Second World War.
He was scooped up by the Americans in the last days of the war and secretly moved to the US where he became an architect of the Apollo space programme that led to the moon landing in July 1969.
On that day half a century ago, ex-SS major von Braun and two fellow German scientists - Kurt Debus and Arthur Rudolph - celebrated with American scientists at Apollo Mission Control Center in Houston, Texas.
But a former concentration camp prisoner says Rudolph would hang victims from a crane if he wasn't happy with their work on the V2 rockets.
The scientists' legacy was revisited last week as the world prepared to mark the 50th anniversary of the moon landing and walk.
Von Braun joined the Nazi party in 1937 and was also an officer of the SS.
He is regarded as a war criminal who helped Adolf Hitler to kill upwards of 9,000 civilians and military personnel, but some have argued he was following Nazi government's orders and had no choice.
It is estimated that as many as 20,000 concentration camp prisoners died in the production of Hitler's secret V2 rockets, which were the world's first long-range guided ballistic missiles.
After being moved to the US, von Braun appeared in Disney's 1955 television special called Man and the Moon.
Speaking with a German accent, he explained how America would put a man on the moon.
His daughter Margrit, who was born in the US in 1952, defended her father's place in history.
She told AFP: "The things that happened during wartime are very difficult to unravel. You may be asked to do things, but it's not like you can say no."
"I don't think people have the kinds of choices that we living in a democracy in America can relate to.
She doesn't appreciate her father being called "the Nazi Wernher von Braun".
She added: "The Americans recruited rocket scientists, and the rocket scientists helped America get to the moon. So I would think that characterisation is more correct."
This week, Tom Bower, recounted his 1987 TV documentary called The Paperclip Conspiracy, which exposed the crimes committed by von Braun’s team and a conspiracy to conceal the atrocities.
Writing in the Mail on Sunday, he recalled the experience of Yves Beon, one of the prisoners who survived the V2 rocket production line.
Rudolph, a Nazi director of production who later became America's director of Apollo production, would hang prisoners from a crane, it is claimed.
Mr Beon said: "If he suspected anyone of not working, he hanged them above the production line and left the body dangling above us for a few days, as a warning. Every week, dozens were killed that way.
"Sometimes an electric crane lifted 12 prisoners at a time, hands behind their backs with a piece of wood in their mouths to prevent them crying out. Every day over 100 people died from exhaustion, starvation or disease."
It is estimated that 2,700 civilians were killed in V2 rocket attacks against London.
Mr Beon said he managed to hide as SS guards killed labourers as American forces approached near the end of the war.
By then von Braun and his scientists had fled.
They were found and secretly taken to the US as part of Operation Paperclip to prevent them from being captured and put to work by the Soviet Union.
Von Braun, the first director of the Marshall Space Flight Center, offered his expertise plus unused V2 rockets and documents from the Nazi regime.
He and his team were eventually put to work on the Apollo space programme.
They first arrived without their families, settling in Huntsville, Texas,
Seven years before the moon landing, he met President John F Kennedy for the test-firing of the type of rocket that would eventually put American astronauts Neil Armstrong, Buzz Aldrin and Michael Collins.
Von Braun died in the US in 1977 aged 65, two years after he received the National Medal of Science.
Rudolph was forced to return to Germany in 1984, and he died in Hamburg in 1996 aged 89.
