On 5th December 1855 Patrick Connolly, who ran the American Hotel in Regent Road had a business meeting with Patrick Mahon before returning to the latter's pub in William Street. On the same day two Irishmen, 34 year ear old Ambrose Dunleavy and his friend George Mackenzie were buying provisions for Mackenzie's forthcoming voyage to Australia. At around 9pm Mackenzie and Dunleavy went into Mahon's pub and the four men played at the bagatelle board.
Everything seemed normal and just before midnight Mrs Mahon cleared the pub and Connolly, Mackenzie and Dunleavy left together. Mahon accompanied them to the corner of Great Howard Street and all three seemed sober and in good spirits, although there was a brief argument over betting. They then went to the American Hotel which was by now closed, but Connolly's wife and her sister were still sat up talking.
The men began playing bagatelle again but an argument again broke out over betting, leading to Dunleavy striking Connolly, who ran inside and retrieved a dagger. There was then a struggle between the two men with Mackenzie trying to intervene, and which ended with Dunleavy being stabbed in the chest.
At 210am two police officers came across Dunleavy in Regent Road after they heard somebody shouting 'police'. He was bleeding heavily from the chest and unable to speak. The officers then saw Connolly and Mackenzie trying to get into the American Hotel, which was about forty yards away and went over to question them, leaving Dunleavy in the care of another officer who had arrived on the scene. Connolly had his trousers down and was bleeding from the thigh. His request to see his own doctor was refused and both he and Mackenzie were arrested, and a search of the street found a bloodied knife.
Dunleavy was taken to the Northern Hospital where he was pronounced dead on arrival. This news was conveyed to Connolly at the North Dock Bridewell and he replied that Dunleavy had stabbed him and he shouted 'police'. He then said that another man wearing a light coloured jacket then appeared from nowhere and stabbed Dunleavy before running away.
Dunleavy's wife Mary was taken to identify her husband's body at 7am. The couple had come to Liverpool to set up business and met Mackenzie, who had come from Sligo, at a lodging house in Carlton Street. The inquest then took place that afternoon, with Mackenzie giving some incriminating evidence against Connolly, who he had never met before. The coroner's jury returned a verdict of manslaughter against Connolly, who was committed to trial at the present Assizes amongst gasps from relatives and friends who were in the courtroom.
On 15th December Connolly was tried before Mr Justice Wightman. Mary Dunleavy said that her husband had never carried a knife and she had last seen him alive at 7pm on 5th December. Mackenzie confirmed that he had never seen Dunleavy with a knife and a surgeon who examined Connolly at the bridewell said that the wound in his thigh could well have been self inflicted.
Connolly's defence counsel suggested that he would not have called for the police himself if he was guilty, and suggested that Dunleavy could have produced he knife. The jury took little notice though and they took only a few minutes to return a guilty verdict. The judge told Connolly that his evidence had been inconsistent and he had no doubt that he had inflicted the thigh wound upon himself. Connolly then showed no emotion as he was sentenced to be transported for twenty years.