Joseph Basha's body was discovered in the city last Wednesday and Hong Kong police had told The Canadian Press an initial investigation had suggested the death wasn't suspicious.
Police had stated in an email that the body of "an expatriate male aged 25 to 30 was found collapsed inside a public toilet" in the city.
However Phyllis Basha, the young man's mother, tells VOCM radio in St. John's that she'd heard the physical evidence from an autopsy was enough to warrant a criminal investigation into her son's death.
She says police have started working on the investigation, interviewing people who knew her son and looking for video evidence from businesses in the area where his body was found.
Joesph Basha, a musician and student, disappeared on Dec. 21 and his family grew increasingly anxious when he failed to call home at Christmas.
Phyllis Basha said news of the police investigation into her son's death is heartening.
"It makes me feel very good. It wasn't something he did to himself or anything like that," she told the radio station.
"They're pretty convinced there was a criminal behaviour involved."
Basha said police had apologized over delays in beginning their investigation, citing difficulty in locating her son's body at a city morgue.
She said her son's cell phone and wallet were stolen from his body and he was in the morgue as an unknown person for several days.
She declined to provide details of the autopsy or the forensic evidence.
Messages of condolences, have been posted on a Facebook page dedicated to finding the young man.
On her page, Joseph Basha's sister, Cindy, posted a message early Tuesday saying she regrets to say that her "beautiful, talented, sweet brother" was found dead last Wednesday.
"My brother was so loved and had such a significant impact on all of those who knew him. This was a such a tremendous loss for us all,'' she wrote.
Joseph Basha had lived in Hong Kong since 2008 and was studying international and public affairs at the University of Hong Kong.
He was also the lead singer of the band Milkteeth and the work on his ReverbNation web page has over 9,000 fans.
His mother said his sister Jacqueline Berensen, a forensic psychiatrist, and her husband, Alex Berensen, are in Hong Kong and are relaying information to her about the case.
The mother said she has received an outpouring of support from Basha's friends from around the world.
"It's amazing for someone so young to have befriended so many people."