He was hanged on December 7, 1869, on the outside wall of a jail located in Goderich, Ontario, for the murder of his father, Nicholas Melady Senior and his stepmother Ellen.
The murders are believed to have been committed on the evening of June 6, 1868, on a farm in the present day municipality of Huron East, south of the current community of Seaforth, Ontario.
Melady's trial was surrounded by controversy at the time, with allegations of perjury, lost and planted evidence, as well as the unusual use of a female police informant, who posed as a criminal and feigned affection for Melady while he was imprisoned, in an attempt to gain a confession from him.
During the course of the investigation into the crime, seven other members of the Melady family, as well as two other male individuals, were initially jailed as suspects and later released.
On January 1, 1870, three weeks after Melady was hanged, a Canadian federal government Order in Council came into effect that banned all future public executions in Canada.