The story of the Amman Valley’s only unsolved murder is to make it into print after author and Guardian chief reporter Steve Adams agreed a book deal with one of Wales’ most prestigious publishing companies.

Murder at the Star will tell the story of the killing of shop manager Thomas Thomas at the Garnant branch of Star Stores on February 12, 1921.

The brutal crime has remained a mystery for more than 90 years despite the involvement of a team of Scotland Yard detectives, but after 18 months of painstaking research Steve claims he has solved the case and identified the culprit.

Steve plans to reveal the name – and a photograph - of the killer when Murder at the Star is published by Seren Books in early 2015.

“I’m absolutely delighted to have agreed a deal which will allow me to tell the real story of what happened that night,” said Steve.

“Many people in the valley believe they know who killed Thomas Thomas and throughout my research I have spoken with dozens of individuals who have all mistakenly named the same person as the culprit.

“I am in no doubt whatsoever that that man was wholly innocent of the crime.

“From the first days when I began looking into Thomas Thomas’ death the facts just failed to add up and the more I looked into the case, the more convinced I became that the valley rumour mill had got it wrong.

“I know how and why the rumours first began, and it has been interesting to see how village gossip and speculation grew to the point where one simple misunderstanding and an anonymous, unfounded accusation at the dead man’s funeral has seen an innocent man labelled a killer for almost a century.”

Not only is Steve sure he can clear the name of a man wrongly-accused of murder; he also claims he has identified the real killer.

“There is no question in my mind that I know who committed the murder,” said Steve, “and what is more, I am confident I can prove his guilt beyond reasonable doubt.

“I guarantee those who think they know who killed Mr Thomas that they are wrong.

“The real culprit lived in Garnant at the time and was on the fringes of the investigation during its initial stages, but a simple mistake by the authorities during the early days of the inquiry removed him from suspicion.

“It is clear from reading the original case files that the Scotland Yard detectives were never quite satisfied that he was ever completely beyond suspicion, but that early error – and evidence given because of it – ultimately eliminated him from the inquiry.

“That crucial mistake ensured that a killer was never brought to justice and that the murder at Star Stores has remained unsolved for all this time.”

Steve recently agreed a deal with Bridgend-based Seren Books to publish Murder at the Star as part of their spring catalogue in 2015.

“I am absolutely delighted to have teamed up with Seren Books,” said Steve.

“Their roster of authors reads like a Who’s Who of Welsh writing so to add my name to that list is a real honour.

“To have my book alongside the likes of Welsh greats such as RS Thomas, Dannie Abse and Edward Thomas is an incredible achievement.

“Most journalists will secretly tell you that they hope one day to get around to writing a book, but to have a deal in place for one which will bring the history of the area to a national audience, clear the name of an innocent man and also solve the Amman Valley’s only unsolved murder really is beyond my wildest expectations.”

Murder at the Star is due to be published by Seren Books in spring 2015.

If you have any information you might like to share with Steve, you can contact him at the Guardian, visit his website or follow @murderatthestar on Twitter.