On 24 October 1890, Mrs. Hogg, with her baby, called on Pearcey at her invitation. At around 4:00 p.m., neighbours reportedly heard screaming and sounds of violence. That evening, a woman's corpse was found on a heap of rubbish in Hampstead. Her skull had been crushed, and her head was nearly severed from her body. A black perambulator was found about a mile away, its cushions soaked with blood. An eighteen-month-old child was found dead in Finchley, apparently smothered. After the adult body was initially speculated to be that of an 'unfortunate' in the press, it was eventually identified as Phoebe Hogg, with the toddler's body being that of her daughter. Mary Pearcey had been seen pushing baby Tiggy's perambulator around the streets of North London after dark. The police searched her house, and found blood spatter on the walls, ceiling, a skirt & apron, as well as matted hair & blood on a fireplace poker and carving knife. When questioned by the police she said that she, 'had a problem with mice and was trying to kill them'. Sir Melville Macnaghten wrote that Pearcey would later respond by chanting, "Killing mice, killing mice, killing mice!".