Toronto homicide investigators need the public's help to understand why a 21-year-old man was found shot to death in the back seat of his own car, some 19 hours after two males dropped the vehicle off at a plaza with the man still inside.

Det. Andy Singh laid out the unusual circumstances surrounding the death of Amir Naraine at a news conference at police headquarters on Monday.

Singh released video surveillance that shows Naraine's black Chevrolet Malibu pulling into a parking spot at a strip mall in the city's northwest corner at 12:15 a.m. on Sept. 29.

The video shows two males get out of the car, open the trunk, close it and then walk away. They left Naraine in the back seat, Singh said.

"We believe that Amir was with these individuals prior to his vehicle being dropped off," he said.

Around the same time, Naraine's family called police to report their son missing, Singh said. He was last seen alive "much earlier" the previous day, he said.

"I've spoken to his parents -- they're still looking for answers, they're very confused and totally distraught," Singh said.

"Nothing in their mind can explain why he was in the back seat of his own car."

At the time, investigators said someone had reported seeing a man passed out in a car around 7:30 p.m. When paramedics arrived, they found the man dead with multiple gunshot wounds, Singh said.

Singh said police believe Naraine was not killed at the plaza, and that there is likely a secondary crime scene somewhere.

Police have called the two individuals "persons of interest."

"I'm releasing this video footage in the hopes that these two individuals come forward and speak to me as I believe they have very critical information as to why and what happened to Amir," Singh said.

The detective is also hoping friends and the public can help fill in "time gaps" as they reconstruct Naraine's movements in the hours and days before his death.

This report by The Canadian Press was first published Oct. 21, 2019.