Chun Qi Jiang is charged with first-degree murder in the death of 41-year-old Guang Hua Liu, whose body parts were found in parks and waterways in August 2012.
Crown prosecutors allege Jiang killed Liu, with whom he had an on-again, off-again relationship, after she spurned him for a new boyfriend.
But the defence says it was Jiang's 66-year-old mother who fatally stabbed Liu during a dispute over allegedly stolen jewelry, then cut her body into pieces.
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Jiang only helped cover up the gruesome crime to protect his mother, who died shortly after his arrest, his lawyers say.
Should the jury have any reasonable doubt about whether Jiang killed his ex, they must acquit him, Ontario Superior Court Justice Gisele Miller said in her final instructions Wednesday.
In order to convict him of first-degree murder, they must find he deliberately set out to kill Liu or cause her potentially fatal harm, Miller said.
If they find he meant to kill her, but did not plan to do so, he must be found guilty of second-degree murder, she said. If, however, they find he killed her but did not mean to, the verdict must be manslaughter, she said.
During the four-week trial, court has heard from the Crown that Liu's head showed more than 40 "chop-like'' wounds caused by a sharp-edged object, possibly a hatchet or cleaver.
The trial has also heard Liu's blood was found in the accused's basement and in the trunk of his car, while a pair of rubber gloves found in a kitchen drawer tested positive for both Liu and Jiang's DNA.
In his closing arguments Tuesday, Crown attorney Brian McGuire argued the brutality of the assault on Liu, coupled with the careful eradication of any evidence that might point to her death, prove she was never meant to survive.
That Liu suffered dozens of injuries to vital parts of her body shows she was under a "persistent attack" meant to cause fatal harm, McGuire told the court.
Jiang was familiar with the areas where her remains were dumped and made sure to leave her head, the most identifiable part, as far away from his home as possible, while still giving himself time to clean up the scene of the crime, he said.
"He was not going to let her live. Part of the plan was that she was going to die and he was going to make sure of it," he said.
Prosecutors also suggested Jiang's ailing mother would not have been physically able to overpower a fit, 41-year-old woman and walk away "without so much as a scratch."
The defence, meanwhile, told jurors not to punish Jiang simply "because someone needs to be punished."
Jiang testified he did not call police or an ambulance after the grisly incident that took place in the basement of his home. He admitted to bringing up parts of Liu's body to be washed in the kitchen sink and packing them in plastic bags, but insisted it was his mother cut up the body.
He also told the court he put Liu's torso into a suitcase, went through the contents of her purse and put her belongings in bags to be disposed of with her remains.
While "despicable," those actions do not make him a killer, defence lawyer Kathryn Wells said in her closing arguments Tuesday.
Jiang was arrested on Aug. 26, 2012, and originally charged with second-degree murder but the charge was upgraded to first-degree murder last summer.
Liu's foot was found in Mississauga's Credit River on Aug. 15, triggering a massive investigation. Her head was discovered the next day in the same river, wrapped in grocery bags.