No arrests have been made, and the only solid lead disclosed by police involves two black men seen fleeing the scene in a small silver car.
The pair is thought to have either witnessed the shooting or to have been the intended targets.
At the time, 6:30 p.m., the street was packed with shoppers and homeward-bound residents, several of whom gave statements to police.
But after the first day of the investigation the flow of information swiftly dried up, much to the homicide squad's dismay.
Now witnesses appear to be responding to a fresh appeal for assistance. Along with at least two anonymous Crime Stoppers tips, four people stepped forward yesterday and will be interviewed, Det. Gray said.
Hours of closed-circuit surveillance tape are also being scrutinized.
Tomorrow evening on Gerrard Street, meanwhile, at the exact time and place of Mr. Mao's death, a Chinese-language flyer will be handed out seeking further help.
Later in the evening, Mr. Mao's family will hold a ritual at the site of his death, stemming from the belief that a soul taken by such violence could remain in a sort of limbo.
At around 9 p.m., a monk will bring to the crime scene a piece of Mr. Mao's clothing that will be used to summon his soul to the Wing Sung Funeral Chapel on Spadina Avenue, where his body has been laid out in preparation for his funeral Friday.
A recent arrival to Canada and the father of two young adults, Mr. Mao was standing on the street stacking oranges when he was killed.
His death struck a public nerve, marking the second gun killing of a bystander in Toronto in under a week: A shooting on Yonge Street in the early morning of Jan. 12 claimed the life of 42-year-old John O'Keefe as he was walking home.
Det. Gray said she remained hopeful the killing will be solved but refused to speculate on what sparked the gunplay.
"It doesn't matter to me frankly, I can't imagine what motivation there might be," she said.
"There was some kind of argument between two groups, but I refuse to speak to motive because then it becomes like an excuse - and there's no excuse, right?"
Yesterday Toronto Police Chief Bill Blair moved to assuage public anxiety over the two deaths during questioning by the Police Services Board.
"It's important to keep these things in perspective," he said.
"There were three such events in all of 2007. So far this year there are two. It is not indicative of a trend. It is worrisome ... but I don't think it is proof that the city is unsafe."
Chief Blair said the federal government does not support his call for a firearms ban in Ontario, but that proposed federal legislation to introduce new offences, increase mandatory minimum sentences and reform bail conditions for gun offenders has "great promise."
He said that while police have made great strides in dismantling gangs and engaging the community, policing is only one aspect of the battle, which includes stemming the availability of firearms and streamlining the prosecution of offenders