Many of the cold cases involve victims of gun violence, which has been an ongoing problem in the city for many years, reports The Toronto Star.*
Out of the several-hundred unsolved cases, some are remarkably puzzling and interesting.
One of the victims is the child of a prominent Toronto activist whose oldest child was murdered on a separate occasion.
Another was at a house party with 100 guests at the time of his murder, and yet, the trail went cold.
Here are a handful of Toronto's most mysterious cold cases.
Anandavel was 15 years old when she went out on Saturday, June 12, 1999. She was last seen leaving her home at approximately 9:00 a.m.
In October 1999, her remains were found buried at Finch East Park. Police have yet to name a suspect.
Holly Anne Painter
Holly Anne Painter was murdered in 1995. She disappeared on Monday, June 26, and was last seen in a car with two other individuals.
Eighteen-year-old Painter was never seen again after entering the car and police now believe she is deceased.
Flagiello was only 18 years old at the time of his death on November 11, 2009. The Toronto Star describes him as being a victim "in the wrong place at the wrong time."
Flagiello died ushering his friends to safety during a shooting at a music studio. To this day, Toronto police don't know who took his life.
Nineteen-year-old Tina Picoulas was found inside the Comfort Hotel at 445 Rexdale Boulevard on May 29, 2008, but no one knows how she ended up there.
She was alive and suffering from medical trauma when police arrived, but was later pronounced dead. There is still no information about what happened to Picoulas.
Tristan Wright died during a house party with 100 other people in attendance, and yet no one knows who killed him.
He was 23 years old at the time of his death which took place on February 17, 2008.
Karim Rashid Ata-Ayi
Ata-Ayi was shot outside his apartment building on Sunday, December 23, 2007, at about 2:30 p.m. He was 29 at the time of his death.
He was one of two sons of prominent Toronto activist Patricia Wynter who co-founded United Mothers Opposing Violence Everywhere (UMOVE). Wynter's oldest son was also a victim of a homicide.
Patricia Lupton is the oldest Toronto Police Service cold case. Patricia was only 12 when she was discovered in medical distress on the side of the road on Monday, March 9, 1959.
Lupton was pronounced dead on the scene and was last seen alive en route to Kennedy Park Plaza sometime after 5:30 p.m.
Almost 60 years later, no one knows what happened to her.
*Editor's note: This article has been updated.