Police issued a news release on Sunday evening, saying the death of an employee at a Shell station on Marlee Avenue on Saturday night is being treated as a suspicious death investigation.
It was previously being investigated as a vehicular homicide.
Investigators have identified a 39-year-old Toronto man as a person of interest. They are urging him to call a lawyer and make arrangements to contact police.
Police say the person of interest they are seeking was driving a four-door Isuzu Rodeo that is silver or beige and "may have stolen plates attached to it."
The person is described as a five-foot-five white male, with a dark complexion, who weighs 220 to 230 pounds. He has dark-brown hair.
SUV fled station after filling up tank
Earlier on Sunday, police said a man had filled up his SUV with $112.85 in fuel at a Shell station at Marlee Road and Roselawn Avenue the night before.
The man allegedly attempted to leave the station without paying by turning onto westbound Roselawn Avenue.
"Our investigation has thus far revealed that the driver of that vehicle had gone into the gas station, fuelled up and attempted to drive away without paying, and that's when this tragic event occurred," Staff Sgt. Courtney Chambers told CBC News on Sunday afternoon.
Police said a 44-year-old man working at the gas station was struck and dragged by the vehicle.
The victim suffered life-threatening injuries and was transported to hospital, where he died.
Anna Lapenna, who lives across the street from the gas station and saw the incident unfold, said she ran over to try to help the victim, but "he was lifeless" by the time she got there.
Police were called to the scene just after 9 p.m. ET.
Shell released a statement saying the company is "saddened by this senseless loss of life," adding that it is co-operating with police in the investigation.
Chambers said police frequently receive calls for so-called "drive-offs" at gas stations where customers fill up and flee the scene.
"It's a frequent occurrence in and around the city where folks gas up and they drive off," he said.
"Some blame it on the price of gas, but at the end of the day, it's still stealing."
Shell officials told CBC News that its employees are not supposed to intervene if criminal activity unfolds at one of its facilities.
Man killed in similar incident last year
This is not the first time a gas station attendant has been struck and killed in the Greater Toronto Area.
In May of last year, a 62-year-old man suffered injuries at a Mississauga gas station after he tried to chase down a driver for not paying. The station employee died in hospital days later.
A 22-year-old man was arrested five months later and charged with criminal negligence causing death, fleeing the scene of a fatal accident, theft under $5,000 and breach of recognizance.
At least one province has brought in laws to prevent these types of fatalities.
British Columbia requires customers to pay for their gas before filling up their cars. That rule came into effect after a young man died in Maple Ridge while trying to prevent a robbery.