A Toronto woman accused of murdering her severely disabled daughter insisted in court Tuesday the teen died following an alleged home invasion.

Cindy Ali has pleaded not guilty to a charge of first-degree murder in the death of 16-year-old Cynara Ali, who had cerebral palsy and couldn't walk, talk or feed herself.

Crown prosecutors have argued Ali murdered Cynara in February 2011 by smothering her with a pillow. They accuse the defendant of trying to cover up the crime by spinning an elaborate web of lies about two men breaking into her home.

On Tuesday in a Toronto courtroom, Crown prosecutor Rosemarie Juginovic asked Ali why she didn't pull an alarm near the front entrance instead of running to a phone in the kitchen, and why she threw steak knives at one of the alleged assailants who was holding a gun.

Ali insisted she was only thinking of her daughter and protecting her.

She told the court one of the men took her to the basement of her home while his accomplice remained in the living room with Cynara.

"If what you're describing is real, no mother, no father would have left their daughter alone with that man who was holding a pillow in his hands," Juginovic said. "Not one."

Ali testified she called 911 after she shook her daughter gently and Cynara didn't respond, but said she passed out while she was on the phone with the operator. When paramedics arrived, they found Cynara without vital signs.

She also told the jury she had been injured by the two men, but the crown argued that the hospital didn't find any injuries on Ali.

"There's not a parent who loves their child who would feel their own pain when their child is dead or dying on the couch," Juginovic countered.

The court also heard that a letter arrived at the Ali home weeks after the alleged break-in. Ali testified it was from the criminals explaining they were looking for a package and that they had targeted the wrong house.

Juginovic insisted Ali wrote the letter but she denied the accusation.

Closing arguments begin Thursday and the jury is expected to begin deliberations on Friday.

With files from Canadian Press