The ex-wife and her common-law husband have been accused of murdering a Mississauga man and his mother, who died three years apart, Peel police say.

Melissa Merritt, 33, and Christopher Fattore, 36, were arrested Tuesday morning in Halifax in the deaths of Caleb Harrison and his 63-year-old mother Bridget. Merritt and Caleb Harrison were married until 2005.

Both accused, who moved to Bridgewater, N.S., shortly after Caleb’s death, will make a court appearance in a Halifax courtroom Wednesday morning and will be flown back to Brampton on Friday, Insp. George Koekkoek said during a news conference on Tuesday.

Emergency crews found the body of Caleb Harrison in a home on Pitch Pine Crescent, near Burnhamthorpe Road and Winston Churchill Boulevard, around 12:30 p.m. on Aug. 23, 2013. It’s the same home where his mother died in 2010.

Koekkoek said the Harrisons were asphyxiated but declined to provide a motive or indicate the roles the accused played in the alleged offences as the case is now before the courts.

Police have now also reopened the investigation into the April 2009 death of Caleb Harrison’s father, William, who also died in the same home. Investigators originally determined he died of natural causes, but they are taking another look and are treating his cause of death as undetermined.

Caleb Harrison was last seen the evening before his death at Erin Gate Park in the Renforth Drive and Eglinton Avenue West area. At the time, he was coaching a baseball game with his two children. Police said there was some phone activity after that.

Merritt was previously convicted of parental abduction of the children she had with Harrison — an abduction Koekkoek said occurred around the same time as Harrison’s father’s death.

Fattore and Merritt have children of their own and they are all being cared for, Koekkoek said.

With files from The Canadian Press