While bringing hot water to the room of Alexander Bonaparte Cust, she came upon him washing in the basin. She noticed that his sleeve was all wet and the water in the basin was red. At first this did not register but later when news came out that there had been a murder in Doncaster, she screamed that it must have been blood in the water. She did not want to get involved with the police but her boss, Mr Ball encouraged her and brought her to see Inspector Crome. On the strength of her report, two policemen were sent to the hotel and conducted a search which yielded results.
Mary Stroud was also able to describe Cust as medium size, "stooped and wore glasses", in a dark suit and homburg hat. "Rather shabby looking".
Mary Stroud is described as a plump young woman with round eyes clearly in a state of high excitement.