BRAMPTON, Ont. -- A 10-year-old boy's father and stepmom are both to blame for the months of abuse and starvation he endured and were "equally capable" of delivering the brutal beating that ended his life, a defence lawyer told the couple's murder trial Wednesday.

The case hinges on which one of them did batter Shakeil Boothe until the blood seeped out of his muscles and flooded his emaciated body, lawyer John Rosen told a Toronto-area court.

"He was dead on their watch -- both of them," said Rosen, who represents the father. But only one of them committed murder, he said.

Court has heard both Garfield Boothe and his wife Nichelle Boothe-Rowe, who are charged with second-degree murder, had possible motives for wanting the boy gone.

Shakeil came to Canada from Jamaica in 2009 in search of a better life, but quickly became an embarrassment for his father, a volatile and violent man who ruled his home with an iron fist, Boothe-Rowe's lawyer Brian Ross argued.

Boothe-Rowe resented Shakeil -- her husband's child with another woman -- and was fixated on becoming a mother herself, Rosen alleged. Her dislike of Shakeil only increased after the couple had a son of their own, he said.

Prosecutors allege Shakeil was deprived of food, chained to his bed and regularly whipped with a belt until he bled in the months leading up to his death.

Court has heard autopsy results showed the boy suffered heavy blows that overwhelmed his body, already weakened by malnutrition and severe infection.

Both accused have testified to finding Shakeil's lifeless body on May 26, 2011 -- a full day before his death was reported to authorities -- but they gave vastly different accounts of what happened that day and in the months before.

Boothe admitted on the stand he regularly struck his son with a belt for discipline, but denied allegations of long-term abuse and maintained he didn't lay a hand on Shakeil the morning he died.

He said it was his wife's idea to chain the boy to his bed during the day because she wasn't able to control him when his father was out. And Boothe-Rowe was home with Shakeil the morning he was found dead, her husband said.

"That day, that morning, he did not kill his child," Rosen said. "What happened that day is that Nichelle Boothe-Rowe committed murder."

Court has heard a children's aid worker called the family's Brampton, Ont., home that day and spoke to a male speaker, who identified himself as Daniel.

Rosen suggested it was Shakeil who picked up the phone, sending his stepmother into a fit of rage. Terrified that child services would take her baby away after seeing Shakeil's condition, Boothe-Rowe "must have gone ballistic" and beaten the boy to death, he alleged.

She spent the next two and a half hours cleaning up the mess, planning her escape and plotting to pin it on her husband, who had already been convicted in a spousal abuse case, Rosen said.

When she finally called Boothe at work around 11:20 a.m., she pretended Shakeil had died from the cold he had been fighting for weeks, the lawyer alleged.

Boothe-Rowe, meanwhile, testified her husband woke the boy at dawn to give him cold medicine before leaving for work. Hours later, she found him cold and without vital signs on the basement floor, she said.

She told the court her husband had been chaining Shakeil to his bed for months, intermittently at first but then daily. She would secretly free the boy during the day, she said.

Aside from her husband's testimony, there is no evidence Boothe-Rowe abused Shakeil, her lawyer said.

"You cannot find that Nichelle beat and chained Shakeil based on the testimony of this admitted liar," Ross told the jury, listing off lies Boothe admitted telling police, school officials and his probation officer.

Fear for her own life kept Boothe-Rowe from intervening openly on Shakeil's behalf, her lawyer said.

Boothe-Rowe admitted she didn't do enough to help Shakeil Boothe, but she did not intend for the boy to die or suspect it could happen, which would be required for a murder conviction, Ross said.

"She didn't want this to happen," he said. "She wasn't encouraging or helping him in any way to make it happen."

There is no doubt Boothe-Rowe failed in her duty to protect Shakeil, but while her inaction may make her seem despicable, "we don't convict people in Canada for being despicable," he said.

Boothe-Rowe was under duress due to the abuse she herself suffered at the hands of her husband and should be acquitted of all charges, Ross said in his closing arguments.

"She believed that if she did anything that would get Garfield in trouble, she would end up dead."

Prosecutors will present their closing arguments Thursday.