Vancouver police have released video surveillance footage captured in the minutes leading up to the death of a homeless man earlier this month in hopes it will generate more leads in the investigation.

The well-liked 55-year-old, dubbed Tom Sawyer, was found by emergency responders in grave condition behind an apartment building in the downtown core early on March 7. He died shortly after being taken to hospital.

On Friday, police released video footage showing the man walking into the alley behind 928 Richards Street holding a bunch of flowers at around 1:15 a.m. Just over a minute later, a small sports utility vehicle goes by and pulls west onto Smithe Street. Two men are seen entering the alley about a minute-and-a-half later. They exit after approximately 40 seconds.

Another four minutes passes before someone calls 911 to alert police.

Const. Jana McGuinness said investigators are hoping people can provide information, even tiny details, to help piece together the timeline.

"If it sparks a memory we're just asking for a little bit of information that might make us find out what happened to Mr. Sawyer," she told reporters at a press conference Friday morning.

McGuinness said Sawyer died from severe blunt trauma and internal injuries but investigators can not determine if his injuries are consistent with being struck by a vehicle or an assault.

"What caused those injuries is still under investigation," she said. "We can't rule anything out at this point."