NORTH TONAWANDA, N.Y. — The disappearance of the businessman was initially handled as a missing person case. Then a detective noticed specks of blood near a cellar door and a fisherman found a human torso in the Niagara River.

It was 1997, and when investigators identified the remains as those of William L. Rickerson, they zeroed in on Richard W. Matt, a former convict who had been hired by Mr. Rickerson, and whose name was familiar to law enforcement officials in and around this town north of Buffalo.

Eventually convicted of killing his boss, Mr. Matt is now at the center of the biggest manhunt in the nation after and he and another inmate, David Sweat, escaped from a maximum-security prison in Dannemora, on the northeastern edge of the state. Mr. Matt was serving a sentence of 25 years to life with no chance of parole before 2032.

For the authorities who investigated the murder of Mr. Rickerson, who was beaten and dismembered, news of the escape was an alarming reminder of Mr. Matt and his brazen efforts to elude the police.