In a dusty attic in the Yorkshire hills sits the life’s work of John Kingston, a man who spent decades investigating whether his own stepfather, Stanislaw Chrzanowski, was, in fact, a Nazi war criminal.

Whilst most knew ‘Mr Stan’ as a friendly pensioner, growing fruit for his neighbours and zipping around his village in the Midlands on his mobility scooter, John was convinced he was hiding a dark secret. Unable to shake the terrifying bedtime stories his stepdad told him as a child, John spent his adult life trying to expose the truth.

When John died in 2018, the year after his stepfather, the files, photographs, and hours of secret recordings he made were left boxed up in his attic, until now, when they were discovered by BBC journalist Nick Southall.

Nick has been investigating the extraordinary story of Stanislaw Chrzanowski for over 5 years, trying to establish if this man, who settled here to help Britain rebuild after the war, had also helped the Nazis kill tens of thousands of Jews in his homeland of Belarus.

Told using the archive of secret recordings found in John’s attic, and hearing from eyewitnesses who knew Stan Chrzanowski as ‘a butcher’, this often chilling story takes us from Birmingham, to Berlin to the Killing Fields of Belarus. In it, Nick seeks to answer two questions - was ‘Mr Stan’ the monster his stepson believed he was? And, if so, what was the real reason he never saw justice for his crimes?

Reporter: Nick Southall