A jury in Brampton, Ont. is now weighing the fate of a couple accused of killing three family members -- one by one over five years -- all over an extended child custody battle.

Christopher Fattore and his common-law partner, Melissa Merritt, are accused in the deaths of Merritt’s ex-husband, Caleb Harrison, as well as Caleb’s mother and father, Bill and Bridget Harrison.

Merritt and Caleb Harrison had two children and split up in 2005, the same year she and Fattore met. Fattore and Merritt had four more children of their own.

The Crown’s theory is that Fattore first killed Bill Harrison, 65, in his Mississauga home in 2009 – the same day that Merritt and Fattore were accused of abducting the children Merritt shared with Harrison. Merritt was convicted of parental abduction in 2010.

The Crown alleges Fattore killed Bridget Harrison in the same home one year later -- the day before she was to testify at Merritt’s parental abduction trial.

Three years later, in August, 2013, the Crown alleges Fattore snuck into the Harrison home once again and beat Caleb Harrison with a baseball bat while he slept, before strangling him to death.

Melissa Merritt is accused of first-degree murder in the deaths of Caleb and Bridget Harrison. Fattore is facing the same charges, as well as a second-degree murder charge in the death of Bill Harrison.

Court has heard that it was only after Caleb Harrison’s death that police began to suspect that the deaths of all three Harrisons might be connected. They brought Fattore in for questioning in January, 2014. Thirteen hours into that interview, Fattore allegedly confessed to detectives: "I killed Bridget Harrison and Caleb Harrison."

Jury members watched the video clips of Fattore’s alleged confessions. With respect to Bridget Harrison, he said he first hit her a few times. "I then proceeded to squeeze her neck until she stopped breathing and laid on the floor," he said.

With Caleb Harrison, Fattore said he snuck into the house and killed him without speaking a word. "He tried to bribe me with money. I didn't speak to him. I just knocked him to the ground and then proceeded to choke him,” he said.

Fattore has denied involvement in Bill Harrison’s death, with his defence team alleging there is no proof the elder Harrison was murdered. In fact, Harrison death’s was not considered suspicious at first, and his cause of death was listed as “acute cardiac arrhythmia.”

When Fattore and Merritt’s three-month-long trial began, he denied the other murders as well, saying he had given police a false confession.

Fattore attempted to plead guilty to manslaughter in Caleb Harrison’s death, saying he only intended to hurt him, not kill him, but the Crown rejected that offer.

As for Melissa Merritt, her lawyer alleges she knew nothing of any of the alleged murders.

With a report from CTV Toronto’s Tamara Cherry