Canadian drug company billionaire businessman Barry Sherman and his wife were both murdered, police believe.
Investigators came to the conclusion after six weeks of investigation, but said there are no suspects.
The founder of pharmaceutical company Apotex and his wife, Honey, were found dead in their mansion on December 15.
Police had originally said the deaths were suspicious, but there were no signs of forced entry and they were not looking for suspects.
Detective Sergeant Susan Gomes said the two were found hanging by belts from a railing that surrounds their indoor pool and were in a semi-seated position on the pool deck.
"We have sufficient evidence to describe this as a double homicide investigation and that both Honey and Barry Sherman were in fact targeted," Det Sgt Gomes said.
She said the pair was last seen alive in the evening hours of Wednesday the 13th of December and were not heard from again until their bodies were found late Friday morning.
"We haven't developed any suspects," Sgt Det Gomes said.
The day after the bodies were found, some prominent news media outlets quoted unidentified police officials as saying the deaths appeared to be a murder-suicide.
That upset the couple's four adult children, who hired their own team of investigators and a pathologist, who conducted second autopsies on the Shermans.
Police have released the home back to the family.
Toronto police investigators have scoured the 12,000-square-foot home, towed away the couple's cars and even checked the sewers in one of Toronto's most exclusive neighbourhoods for clues.
Police have taken 125 witness statements and analysed surveillance video in the area.
Mr Sherman, 75, was known for litigiousness and aggressive businesses practices as he developed Apotex, which has a global workforce of about 11,000.