Peel Regional Police say Hashmukhlal Mistry, 61, killed his 57-year-old wife Manjulaben Mistry and his 91-year-old father in the house they shared in Brampton over the Thanksgiving weekend.
The father has been identified by other media outlets as Dewabhai Mistry.
The possibility of murder-suicide was raised upon discovery of the bodies on Oct. 14.
Investigators say the younger Mistry was known to be suffering from depression following a recent job loss, but had done nothing to indicate to family or friends he might harm himself or others.
The family has been "severely traumatized" by the deaths, police said.
Neighbours told CBC News the couple had two adult daughters who have children of their own.
Police said the cause of death will not be released and that the investigation is now closed.