Police have remained tight-lipped on the circumstances surrounding the death of Michael Page-Vincelli, but, on Friday, investigators confirmed "persons of interest" have been identified and are being investigated.

The Integrated Homicide Ivestigation Team's Cpl. Meghan Foster said charges have yet to be laid after Vincelli was allegedly punched inside a Starbucks on July 12. He died three days later from his injuries.

"Homicide investigations are lengthy in nature," said Foster in an emailed statement to CBC News.

A deadly altercation

According to witnesses, the altercation occurred after a woman threw a cigerette butt out of her car in a Burnaby parking lot near the intersection of Hastings Street and Kensington Avenue.

According to IHIT, the altercation happened in the 6500 block of East Hastings in Burnaby. (Jacy Schindel/CBC)

Vincelli threw the butt back at her.

Moments later, the female driver returned with a man. The pair followed Page-Vincelli into a Starbucks.

According to a witness, the fight started when a woman tossed a cigarette butt out of the window of her car and Page-Vincelli threw it back at her. (Jacy Schindel/CBC)

Witnesses inside the Starbucks told CBC News the man punched Page-Vincelli, who fell to the floor, hitting his head on a counter.

Police confirmed he died of his injuries on July 15.

'It can take some time'

Criminal lawyer Paul Doroshenko says it's not unusual for investigators to take their time in a homicide investigation, especially when there isn't an immediate threat to the public.

"The police collect the evidence. They give that evidence to the Crown prosecutors ... and they make a determination as to whether or not that evidence can make the case — and that can take some time."

He says Crown counsel will only lay charges if there's a substantial likelihood of conviction.

"It could be six months before we see a charge. There is no limitation period on a manslaughter charge, and they might come back years down the road and lay a charge if they feel that they have the evidence."