Peel police think they have solved part of a big mystery that surrounded the deaths of three members of a Mississauga family.
Arrests have been made in connection with two of those deaths.
In 2009, 65-year-old Bill Harrison was found dead in his home on Pitch Pine Cres.
"His death was originally determined to have been of natural causes," says Insp George Koekkoek. The exact cause of death, though, was never determined.
A year later, Bill's wife Bridget was found dead in the same home. This time, police called the death suspicious, but once again, they were not able to pinpoint how she died.
Then came another death within the home. In August 2013, their son, 41-year-old Caleb Harrison was found dead. After the autopsy results came in, police called it a murder.
At that point, Koekkoek says police launched a full investigation into the family's history.
"Evidence gathered through this inquiry opened new avenues of investigation into the death of Bridget Harrison," Koekkoek says. "This new information led officers to the determination that her death was also a homicide."
Police also determined that both Caleb and Bridget were killed by asphyxiation.
Earlier today, police made two arrests in Nova Scotia.
33-year-old Melissa Merritt and her common-law husband, 36-year-old Christopher Fattore, were charged with first-degree murder in Caleb and Bridget's deaths.
Merritt is Caleb's ex-wife. They split up shortly after he was convicted of domestic assault in 2005.
In 2009, while Caleb was in jail for a drunk driving conviction, Merritt took off with their two children. When she returned several months later, she was charged with parental abduction.
Police say the abduction happened around the time that Bill was found dead.
One piece of the puzzle that remains unsolved is how Bill died.
"The cause (of death) is undetermined," Koekkoek says. "We haven't ruled out anything."