A Toronto mother accused of killing her severely disabled daughter appeared to be in shock as her child was in hospital on life support, her trial heard Wednesday as the dead girl's sister took the witness stand.

Amanda Ali was called to testify in her mother's defence and told jurors hearing the case that her disabled sister was considered a blessing, not a burden for the family.

As the girl's life hung in the balance in February 2011, Amanda said her mother was stunned.

"She looked blank, she looked like she was in shock," she recalled.

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

Crown prosecutors have argued that after years of being the primary caregiver for the infant-like Cynara, Ali smothered her daughter with a pillow and then created an elaborate story about a home invasion to cover up the crime.

Ali claimed two masked men in black suits rang her door bell and pushed their way into her home demanding a mysterious package — which they never found — and harmed her daughter, her trial has heard.

She claimed she saw one of the intruders hold a pillow over the girl's face, but later told police she only saw him with a pillow in his hands standing over Cynara, court heard.

Court heard hysterical mother in 911 call

In a 911 call played for the court, a hysterical Ali reporting the purported home invasion was heard saying her baby — Cynara — was not breathing.

The jury has heard that emergency personnel found Cynara with a pillow on her forehead and no pulse but revived her and rushed her to a local hospital. Ali was found on the floor, close to Cynara, with no injuries, the trial has heard.

Amanda, who was 21 at the time, said Cynara was first taken to a local hospital and then transferred to one in downtown Toronto, but her mother was taken to a police station for questioning before being allowed to go to the second hospital.

Eventually the entire family gathered at the second hospital, where Amanda said she was finally able to see her sister.

"I didn't know what to think," she said, as tears streamed down her face in court. "I just see her there in the hospital bed. She had tubes and stuff on her."

Two days after Ali called 911, Cynara was taken off life support, court heard.

At the girl's funeral, Amanda called her sister an inspiration, and said she created beautiful memories for her family, court heard.

Cynara's sister called her 'a blessing'

"She was a blessing for us," Amanda said.

Nonetheless, Amanda noted that Cynara needed to be accompanied by someone around the clock and was known to have lung infections, seizures — she had one the evening before Ali called 911 — and trouble swallowing.

Cynara could express herself by crying and laughing, but didn't always do so at typical times, sometimes laughing when she was in pain, Amanda added.

An autopsy found Cynara's immediate cause of death was a brain injury from deprivation of oxygen, which was caused by cardiac arrest. That cardiac arrest, court heard, could have been caused by suffocation.

A pathologist called by Ali's defence lawyer has testified, however, that he found "no physical evidence" of smothering in the case, but noted he also could not entirely rule it out as a possibility.

He suggested Cynara could have stopped breathing and suffered a cardiac arrest as a result of seizures. He also said a lung infection that was recorded in her autopsy could have been a factor in her death.