A pensioner in Brandenberg, Germany, was casting about with his metal detector last week when it gave an unusual 'bleep'.
According to German media, it's cause was what first appeared to be a nondescript but shiny lump of metal.
Then the 64-year-old hobbyist, Bernd Thälmann, gave it a quick test, reports News.com.au.
It was not magnetic.
This was odd. Bernd had been scouring the terrain around Oranienburg in Brandenberg for some time. He had some experience in what to expect to find.
After bringing it home and leaving it laying around for several days, he and his children began to do some digging on the properties of various metals
What they found caused them to became somewhat anxious.
He notified authorities.
He suddenly became the centre of a huge emergency services effort - including the evacuation and cordoning off of surrounding homes.
Men in hazmat suits moved into his house, and carefully packed his find into a special lead-lined container, which was itself put in a protective suitcase.
Now Bernd's being investigated for possessing 'unauthorised radioactive substances'.
Police have confirmed Bernd's metallic find is radioactive. And they've also reportedly suggested a source.
Oranienburg was, during World War II, the location of a secret research facility.
It was working on enriching uranium oxide sourced from South America..
Its objective was to create weapons-grade plutonium.
This was to be the core a Nazi atomic bomb.
The research facility is long gone.
But it seems some rather telltale traces still remain.
Britain and the United States were well aware of Hitler's atomic bomb ambitions.
They strove hard to disrupt it.
The daring raids by British Mosquito fighter-bombers and British-Norwegian saboteurs to destroy a nuclear research plant in Norway has been the subject of several books and films.
But some 16,000 bombs were dropped on the Oranienburg facility during the war.
It was completely destroyed.
Despite the fact the Soviets carefully scoured the site after steamrollering through Germany in 1945, it's highly likely more radioactive material remains among the scattered rubble.
But Berndt doesn't want to tell police where he found his piece.
He wants to go back there to find more evidence of the Nazi bomb-making project.
"The finder refuses to provide information on the exact location," a police statement reads.
This has landed Berndt in heavy water.
As his find was an "unauthorised radioactive substance", an investigation has been initiated and the find seized as part of an ongoing criminal investigation.
Charges are yet to be pressed, however.
Documents released earlier this year by the US National Archives reveal how close Nazi scientists came to developing the war-winning atomic bomb.
The APO 696 file is a survey of Nazi research concluded Hitler came close to assembling a basic warhead in 1944.
It includes testimony that such a weapon may even have been tested.
The file reports of German test pilot Hans Zinsser believed he saw a 'mushroom cloud' near a nuclear research facility at Ludwgslust in 1944.
His log book - submitted as evidence to Allied investigators - reads; "In early October 1944 I flew away 12-15 km from a nuclear test station near Ludwigslust (South of Lübeck).
"A cloud shaped like a mushroom with turbulent, billowing sections (at about 7000 metres) stood, without any seeming connections over the spot where the explosion took place. Strong electrical disturbances and the impossibility to continue radio communication as by lighting turned up."
A second pilot reportedly observed the same thing an hour later, and an Italian correspondent who saw the blast reported his observations to Mussolini.