Police in Toronto are investigating the circumstances behind the deaths of billionaire founder of Canadian pharmaceutical firm Apotex, Barry Sherman, 75,  and his wife, Honey, who were found dead in their Toronto mansion on Friday.

According to reports, Police found the couple dead after they responded to a medical call at their home at 50 Old Colony Rd. in the Bayview Avenue and Highway 401 area around 11:45 a.m

“The circumstances of their death appear suspicious and we are treating it that way,” said police officer David Hopkinson. Homicide detectives later told reporters gathered outside the home that there were no signs of forced entry.

He also added that two bodies covered in blankets were removed from the home and loaded into an unmarked van on Friday evening. The property is listed for sale for nearly C$7m (£4.1m/US$5.4m).

Reacting to the sad news, Toronto mayor, John Tory, said he was “shocked and heartbroken” to learn of the deaths and noted the couple had made extensive contributions to the city.

“Toronto police are investigating, and I hope that investigation will be able to provide answers for all of us who are mourning this tremendous loss,” he said.

According to Apotex’ website,  Sherman, 75, founded the pharmaceutical firm in 1974. He stepped down as chief executive in 2012 but remained as executive chairman. Forbes has estimated his net worth at $3.2bn.

The firm is the world’s seventh largest generic drugmaker and also said to be largest Canadian-owned pharmaceutical firm with annual sales of more than C$2bn.

It has operations in more than 45 countries, including the United States.