New information will air in the finale of the documentary series 'Did The Right Man Hang?' on Saturday.
It re-examines the apparent murder of a young woman called Minnie Reid in County Armagh in 1932.
Pregnant and unmarried, she was found with her throat cut at a place called the Birches.
A lorry driver called Harold Courtney was subsequently hanged for her murder. Or was he?
The documentary was originally a six-part series but a seventh episode was added after new information came to light at the last minute.
The series is presented by BBC journalist Gordon Adair and produced by his colleague Ophelia Byrne.
They delved into files that had been marked secret for nearly 90 years and tracked down witnesses, with the trail taking them to the other side of the world.
"The final episode is based mostly on an interview with a man who got in touch with us just before Christmas," said Gordon.
"He was in a unique position to give us an insight into several key elements of the story, so much so that we took the unusual step of shuffling the radio schedules to make room for this extra programme."
For Gordon and Ophelia, it has been a challenging and, at times, bewildering attempt to make sense of an increasingly bizarre story.
"At nearly 90 years old, this was the coldest of cold cases," said Gordon.
"All the usual research approaches - talking to people directly involved, wading through BBC archives etc - just weren't available to us."
The pair had to dig deep into whatever records they could uncover, many of which had been classified as secret and closed to the public for decades.
One example of a seemingly innocuous document that provided a key piece of information was a shipping manifest from a trip Harold Courtney made to the US a couple of years before the terrible events of 1932.
"I had been told several times that Harold was very tall, probably six feet," said Gordon.
"His height on the 'admission to prison' documents, however, was 5'9" and we spent a long time trying to find a record of his height which had been independently taken.
"The shipping manifest we had was only one page. It was a listener who pointed out to us the existence of a second page which revealed that Harold had been measured on arrival in the US.
"His height was six feet.
"Those sort of small pieces of the puzzle all helped us to reach a point where we could at least consider making some conclusions about exactly what happened all those years ago in County Armagh."
'Did the Right Man Hang?' is the first series in a new Radio Ulster strand called Assume Nothing where events previously accepted as factual are re-examined by teams of reporters in a bid to find out what really happened.
Episode seven of 'Did the Right Man Hang?' is available as a podcast.
The previous six episodes are available now on BBC Sounds.