Police held a news conference Thursday and said they continue to follow "significant leads" to find Williams's killer, a shooting they describe as the community's "darkest hour."
"We believe this case can and will be solved," said Insp. George Koekkoek.
Williams was hit in the back of the head by a single bullet as he sat in the living room of a townhouse at 51 Ardglen Dr., near Kennedy Road South and Clarence Street. Police say the shot came through the window of the house. Williams was rushed to hospital, where he died of his injuries.
"This was not an errant or stray shot," said Koekkoek. "We believe the person responsible was targeting the residence."
Shooter was standing outside window, police believe
Koekkoek said police believe the shooter was standing immediately outside the window when the shot was fired.
Police say the family, which included Kesean, his brother and mother, had moved into the house a few days prior to the shooting. Police say they have interviewed the previous tenant of the unit.
One theory is that the target of the shooting was a previous resident.
Police say they are frustrated that those who may have information crucial to the case have not come forward.
Police also released three videos of surveillance camera footage captured on the day Williams was shot.
Two of the videos show a man from a distance, running from the scene shortly after the shooting. The person in the video, who police call a person of interest, is wearing a three-quarter length jacket.
A third video shows Kesean and his mother arriving at a local YMCA hours before the shooting.
Police also want to speak to three men who were seen at a nearby plaza at the time of the shooting. Police say they may be witnesses or suspects.
Police also announced a $25,000 reward for information that leads to an arrest and conviction in the case. They've also set up a tip line (905-795-7712) where anyone with information about the shooting can speak to police.
A temporary mobile command unit will also be set up in the neighbourhood to try and drum up new information about the shooting.