A 70-year old mystery has come to an end after DNA analysis proved that the man known as "Prisoner No. 7," who spent over 40 years in Berlin's Spandau prison, was really the Nazi Rudolf Hess and not an imposter. By comparing a surviving blood sample taken from Hess with DNA from a male relative, researchers from Walter Reed Army Medical Center and the University of Salzburg made a positive match with a likelihood of 99.99 percent.

On May 10, 1941, one of the strangest stories of the Second World War began. As night closed in, Nazi Deputy Fuhrer Rudolf Hess took off from an airfield in Augsburg-Haunstetten, Germany in a Messerschmitt Bf-110 fighter plane and flew across the North Sea to Scotland, where he bailed out and parachuted to Earth.

The reason why the second most powerful man in the Nazi hierarchy would do such a thing turned out to be even stranger on questioning by British authorities. It turned out that Hess, fearing that Germany would be caught in a two-front war between Britain and Russia, had decided to make a completely unauthorized flight over the enemy lines to negotiate a peace deal.

The result was far less than Hess had hoped. On learning of the flight after Hess's departure, Hitler rejected the mission categorically and ordered Hess to be shot if he ever fell into Axis hands. Hess himself was arrested by the British and interned in the Tower of London as a prisoner of war.

After the surrender of Germany in 1945, he was handed over the to the war crimes trials in Nuremberg, where he was found not guilty of war crimes, but guilty of crimes against peace and sentenced to life at Spandau, which was a special prison for top Nazis under joint American, British, French, and Soviet control. Hess remained at Spandau until he died from apparent suicide at the age of 93 on August 17, 1987 – at that time, he had been the only inmate for decades

But what made the whole story so bizarre was that a conspiracy theory cropped up soon after his capture. Was the man who died in Spandau really Rudolf Hess or was he an imposter? If he was an imposter, who created him? The Germans? The British? And why? Was he part of a grand deception or just a cover up for Hess's murder by either side?

It was an idea that had a number of causes, beginning with the wild flight to Scotland. Why would a top Nazi do such a thing? Then there were reports after the war that British Intelligence really did consider creating a phony Hess to confuse the Germans by putting a double in his captured uniform. Was this part of the conspiracy?

This was further exacerbated by other factors, such as physical discrepancies between Prisoner No. 7 and the pre-war Hess, his claiming to suffer from amnesia during his trial, questions of his sanity, changes in his sexuality, his refusal to meet his relatives until 1969, and the utter refusal by the Soviets to allow him to be released despite his being the only remaining prisoner in Spandau for 20 years. Even his death became fodder for the conspiracy theory with claims that he hadn't hanged himself with a lamp flex, but had been assassinated.

And this wasn't just a crackpot theory. President Roosevelt doubted Hess's identity, as did Allen Dulles of the Office of Strategic Services (OSS) and Hess's Spandau prison doctor Hugh Thomas, who claimed that the prisoner didn't have Hess's chest scars and that his dental work was different.

Though much of the physical evidence has since been refuted, the question of Hess's identity still had a question mark over it. What is worse, the order to have his remains cremated and scattered at sea to keep his grave from becoming a Neo-Nazi shrine destroyed the most conclusive bit of evidence.

However, in 1982, one of the researchers on the DNA project had worked as a medical officer at Spandau and had drawn blood from Prisoner No. 7 for a routine exam. This blood was hermetically sealed in a slide and later preserved for lecture purposes by the doctor, who still has custody of them.

According to the team, a long detective search tracked down some of Hess's blood relations and DNA swabs were taken from a male relative, (whose identity has been withheld), with an unbroken collateral paternal line to Rudolf Hess. These swabs and DNA from the blood sample were subjected to DNA and statistical analysis, producing a match of the relevant genetic markers that confirmed that Prisoner No. 7 was Rudolf Hess well within the margins of error.

In an interview with New Scientist, Turi King, a geneticist at the University of Leicester, said, "They've got a perfect match with the Y chromosome and a living male Hess relative. If this person was a doppelgänger, you wouldn't get that match, so from that point of view it's a good sign."