Spent cigars, two lighters and match ends were found throughout Apartment 6 at 149 Keyes Ave. early Thursday as fire investigators sifted through debris in the gutted ground-floor unit.
The resident, William H. Stitt, 65, was found dead near a door that would have been his escape to the outdoors. The door was slightly ajar, according to City Fire Battalion Chief Dale C. Herman.
Watertown police Thursday afternoon confirmed that Mr. Stitt was the fire victim, and concurred with the fire department that the "careless use of smoking material" sparked the blaze in his apartment.
Dr. Samuel A. Livingstone, Jefferson County medical examiner, performed an autopsy Thursday afternoon and attributed death to asphyxiation due to carbon monoxide poisoning.
Chief Herman said the fire originated in or near a large stuffed chair in the middle of Mr. Stitt's living room. All other possible accidental causes for a fire were eliminated, he said.
The blaze, which was reported at 8:18 p.m., moved upward into the apartment of Justin T. and Lyndsey Campbell, who smelled smoke and then saw flames. They evacuated, as well as Apartment 7 resident Janet E. England and Apartment 8 resident Christopher Kinsella, Chief Herman said.
Residents of four other units, identified as Phil Harris, Daniel O'Donnell, David Gotham and Frank McIntyre, apparently were not home, he said.
Pets were rescued from the Campbell apartment, he said.
The three-story building owned by Bruce A. Hunter has an interconnected fire alarm system, but Mr. Stitt's apartment was not connected to the system, Chief Herman said. The alarms activated after smoke reached sensors outside Apartment 6, he said.