I first got interested in this true story after listening to a podcast, which stated that Caroline Williams was most probably guilty.  I decided to look further into this, as I do (having written 8 novels based on true stories), and travelled to Kew Archives in London where I was presented with four boxes of information about the case:  court transcripts, police investsigation, witness statements, photos, newspaper cuttings, letters and maps.  I took photos of every page (about 600 pages) and had the massive task of reading through everything to decide if there was a story there. 
Caroline was arrested for slicing through the neck of her husband on Christmas Day, 1937, in Scotland Street, Llanrwst, North Wales. She had told the police that they were the only people in the house, so naturally she was arrested, even though she professed that she loved her husband and wouldn't hurt him. 
Caroline was illiterate, living in a condemned slum.  The lawyer appointed to her defence, obviously thought there was no case there, and put forward the flimsiest of defences. The stuck-up lawyer couldn't be dealing with an illiterate, slum-dwelling gypsy and didn't even put her on the stand at the trial.  The police had found no evidence of anyone else in the area at the time, plus Caroline's sons made things even worse, changing their stories in order to save their mum, giving her a made-up story to tell the court, which effectively blamed someone else.
The lawyer had basically ignored the fact that Caroline had neuritis in her hands, meaning they were constantly painful, numb or burning - she could just about slice a loaf of bread, let alone slice through the jugular, from back to front of her husband's neck. So, this book also brings to light legal injustices.
No, there had to be someone else.  That's where my investigation starts, bringing in a ficticious Cold Case Team, to investigate the case. I also had a lot of people from the area, providing me with information relating to the background of the story - archived newspaper reports and photos. There is also a chapter from a local girl, who was the daughter of the policeman leading the case.
At the trial, the jury had asked for mercy, but the Judge was having none of it, putting on his black cap and pronouncing that she should be hanged, until she were dead.
It doesn't end there....... 

It's available on Amazon as a paperback or ebook: A Llanrwst Christmas: Not Worth Dying For: Amazon.co.uk: Moxom, Ms Margaret: 9798267545822: Books