MONTREAL — He appeared obsessed with the police and owned eerily realistic copies of police uniforms and a homemade replica squad car. He fitted dentures for customers, many of them elderly admirers of his comforting bedside manner. He had a childhood fascination with air guns.

The day after a deadly rampage in a small and sleepy seaside community in Nova Scotia, a picture began to emerge of the killer, Gabriel Wortman, the soft-spoken, seemingly amiable 51-year-old denture specialist behind the worst mass shooting in Canadian history. The death toll totaled at least 19 including Mr. Wortman.

Mr. Wortman, who ran two denture clinics in Nova Scotia, began the massacre late Saturday night in the town of Portapique, a close-knit beachside village of about 100 residents on the Bay of Fundy. It ended 12 hours later at a gas station in Enfield, 55 miles away, with the gunman dead, bodies strewn across a more than 30 mile area, five houses smoldering in flames and 16 crime scenes.

Among the dead, all adults, were a police officer, two nurses and an elementary schoolteacher. Stephen McNeil, the premier of Nova Scotia, described the massacre as “one of the most senseless acts of violence in our province’s history.”