Canadian billionaire Barry Sherman and his wife Honey both died after suffering “ligature neck compression”, police have confirmed.
The 75-year-old drug company founder and his 70-year-old wife were found dead in the basement of their Toronto mansion.
The investigation into their deaths – which were classified as “suspicious” by police – has been taken over by Toronto homicide detectives, although officers say they are not looking for any other suspects.
The couple’s bodies were discovered by an estate agent who was setting up an open house for their luxury home, which had recently been put up for sale for 6.9m Canadian dollars (over £4m).
The Sherman family has angrily refuted any suggestion their deaths could have been a murder-suicide.
“Our parents shared an enthusiasm for life and commitment to their family and community totally inconsistent with the rumours regrettably circulated in the media as to the circumstances surrounding their deaths,” a family statement read.
“We are shocked and think it’s irresponsible that police sources have reportedly advised the media of a theory which neither their family, their friends nor their colleagues believe to be true.”
The family have asked police to conduct a “thorough, intensive and objective criminal investigation” into their parents’ deaths.
Officers were called to the house to attend a “medical complaint” at about midday on Friday, but found no signs of forced entry to the home.
Homicide detective David Hopkinson said: “The circumstances of their death appear suspicious and we are treating it that way.”
Two bodies covered in blankets were later seen being removed from the house.
One of Canada’s wealthiest couples, Mr and Mrs Sherman had given tens of millions of dollars to hospitals, universities and Jewish organisations and were fundraisers for Prime Minister Justin Trudeau’s Liberal party.
In response to the news of their deaths, Mr Trudeau tweeted: “Our condolences to their family & friends, and to everyone touched by their vision & spirit.”
Mr Sherman had set up the pharmaceutical company Apotex in 1974, stepping down as chief executive in 2012 but remaining executive chairman.
Lawsuits from family members, alleging they were cut out of their share of the company back in 1967, had dogged Mr Sherman for decades. All claims against him had been unsuccessful.
Calling the deaths “tragic”, Apotex tweeted to say everyone at the company, which employs around 11,000 staff worldwide, was “deeply shocked and saddened”.
Forbes magazine estimated Mr Sherman’s personal net worth at $3.2bn (£2.4bn), making him the 15th richest Canadian.
“We are at a loss of words,” neighbor Sarah Alva said.
“They are both the most wonderful people we knew and our hearts goes out to their families.”
The couple leave behind four children.