When writing biography, you should understand your subject. After six years of researching William Onion’s life, I came to know him as an honest man. He admitted his many faults and his recollection of events tallied reasonably well with other sources. At the age of eleven he saw a woman executed for theft and claimed that the experience deterred him. All of his convictions were for violence and drunkenness, although some police officers added robbery.

One of his worst acts of violence was on his wife, a few hours after they married. It led to one of the fastest separations in history. When he later referred to a wife, I assumed it was a fantasy, caused by his dubious mental state. I have now discovered that he did marry again, when his first wife was still alive. Bigamy was and is a criminal offence with Onion falsely stating that he was a bachelor on the certificate and giving other incorrect information.

I have yet to find out what happened to Onion’s second wife. He said that a man from Japan violated her and stole his goods. Those close to him said that he smashed his belongings in a fit. The second is more likely, especially now I know he was not always honest.

Paul Williams is a writer of fiction and non-fiction best known for his Jack the Ripper Suspects: The Definitive Guide and Encyclopedia.