The deaths of Canadian pharmaceutical tycoon Barry Sherman and his wife were "targeted" homicides, Toronto police ruled Friday after a six-week investigation.
No suspects have yet been identified.
The 75-year-old chairman of Apotex and his 70-year-old wife Honey were found dead in their Toronto home on December 15. Apotex is the largest maker of generic drugs in Canada, and the Shermans' fortune was estimated at Can$4.7 billion (US$3.8 billion).
"We have sufficient evidence to describe this as a double homicide investigation, and that both Honey and Barry Sherman were, in fact, targeted," Susan Gomes, a Toronto police homicide detective leading the investigation, told reporters.
Gomes confirmed the couple were last seen alive or heard from the evening of December 13, two days before their bodies were discovered.
She said there were no signs of forced entry at their home, where they were found in a basement pool area, "hanging by belts from a poolside railing in a semi-seated position on the pool deck."
"They were wearing their clothing," she added.
Gomes declined to discuss suspects, except to say: "We have an extensive list of people that we're looking forward to speaking to" about the case.
The investigation so far has included sweeps of two homes owned by the Shermans, as well as Barry's workplace at Apotex.
Police also compiled 127 witness statements, canvassed the couple's neighborhood for clues and collected some 2,000 hours of surveillance video from homes and businesses in the area.
"We certainly believe that we've captured images of people that were in the neighborhood" on the night of the killings, Gomes commented.
Authorities had initially suggested the deaths were caused by double suicide or murder-suicide, calling them "suspicious" after an autopsy concluded the couple died from "ligature neck compression," or strangulation from tying or binding.
But the Shermans' children strongly refuted that early conclusion, and hired a lawyer and private investigators to review the evidence.
A separate autopsy was also performed by a forensic pathologist on December 20, just before the couple's funeral.
The pathologist and private detectives found markings on the victims' wrists indicating that their hands had been tied with cords or plastic zip ties, according to the Toronto Star.
When the bodies were found, the wrists were untied, without rope or cords nearby, the newspaper said. Furthermore, toxicology tests on the bodies showed no signs either victim had been drugged.
Sources close to the family probe used words like "professional," "contract killing" and "staged homicide" to describe the couple's death, the Star said.
The Sherman family acknowledged the police's double homicide determination, saying: "This conclusion was expressed by the family from the outset and is consistent with the findings of the independent autopsy and investigation."
Sherman founded Apotex in 1974, and over the following decades became known as a ruthless and litigious businessman who shunned the limelight while revolutionizing the drug industry in Canada.
Today, the company employs more than 11,000 people and sells 300 generic drugs in 120 countries.