Toronto's homicide unit has taken over a probe into the "suspicious" deaths of Canadian pharmaceutical billionaire Barry Sherman and his wife Honey, police said Sunday after finding they had died of strangulation.

"The cause of death for both deceased was ligature neck compression," Toronto police said in a statement following post-mortem investigations of the bodies of the 75-year-old chairman of the board of Apotex and his 70-year-old wife.

"Toronto Police Service Homicide has taken the lead in this suspicious death investigation."