By Geoffrey Seed, author of A Place of Strangers.
Many years ago, when I was working as a producer of TV investigations, I met an old diplomat for supper. He was a man straight out of a John le Carre thriller: a man who once did favours for Israeli intelligence in situations where it was best not to be a Jew.
He told me a fascinating tale. A contact had admitted hunting down several ex Nazis well into the 1950s and 'arranging' their suicides or accidental deaths. These were in the days when senior officials of the Third Reich were still living in secret across Europe and South America, escaping justice for their terrible crimes.
It was a terrific story from an impeccable source. He named a millionaire he believed had more knowledge.
We met amid the antiques and artworks of his mansion. Yes, he knew the diplomat's contact. Yes, there may be truth in what was claimed. But no, he couldn't - or wouldn't - confirm any specific death.
As for going on camera for a documentary or being quoted in any newspaper piece - hell would become an ice rink first.
So I began to clock up air miles. But however many interviews I conducted with one-time Jewish resistance fighters, spooks or relatives of ex-Nazis, I couldn't get the degree of legally viable corroboration needed.
I did, of course, meet the diplomat's original source. He hadn't long to live but ill though he was, there remained a fearsome steeliness within the heart and bones of the man.
Some information he offered seemed at odds with the historical record. I couldn't be sure if this was him dissembling to shake my confidence in the story.
Should what he'd allegedly admitted to the diplomat be correct, this frail but flint-hard pensioner had got away with murder. He wasn't about to make a death-bed confession.
Yet when we talked of a particular 'suicide', his remarks were more detailed and delivered with such quiet intensity, it was tempting to suspect he might have been present when it took place.
But when pressed further, he waved me away saying: 'You'll not draw me inch by inch into telling you anything I couldn't have made up.'
I flew home with a file of research notes about the lives and times of some extraordinary people but no supporting proof of what I was really after. This intriguing bit of secret history - if true - would soon go to the grave with those who took part in it.
So, like the thieves and beggars journalists are, I've made up a story, added a love affair and a few observations from a life on an occasionally bumpy road and called it A Place of Strangers. But don't forget - some of it is true.
Geoffrey Seed is author of A Place of Strangers, published by Endeavour Press.