An Edmonton mother has pleaded not guilty of killing her daughter in December 2016, with her defence team alleging she suffers from mental illness and should not be held criminally responsible.

On the first day of Christine Longridge's second-degree murder trial, her defence counsel and the Crown submitted an agreed statement of facts. It showed that Longridge has admitted to stabbing her 21-year-old daughter, Rachael, in order “to cause her death.”

Defence attorney Dino Bottos argues his client should be found not criminally responsible because she thought she was acting on the voice of a higher being at the time of the killing and did not know that stabbing her daughter to death was morally wrong.

“She did it to fulfill what I would call a ‘messiah mission,’” Bottos told reporters outside the courthouse Wednesday.

“In order to save her son Michael, who she thought was the messiah, she was compelled to kill Rachael and then herself.”

Before her death, Rachael Longridge had graduated at the top of her nursing class and was about to start a new job at an Edmonton hospital. On the night of her death, her mother attacked her with a cleaver, leaving her nearly decapitated.

The Crown opened and closed its case Wednesday after entering the agreed statement of facts, a report from the medical examiner and a recording of the mother’s interview with police.

The defence called two witnesses. One was Don Metz, a longtime family friend, who described Longridge as a "loving supportive mother,” someone who was "quiet, shy, but always seemed normal." He said "nobody saw this coming."

Longridge's sister Marilyn Hamilton offered emotional testimony in which she said that Longridge's children "were her world” and that "she did not know what she did that day."

Longridge was diagnosed with bipolar disorder after her son Michael was born.

In 2013, CTV News spoke with Longridge about her husband's cancer battle. When he died two years later, friends and family say Longridge’s mental condition worsened and she began taking her medications less often.

Longridge is now being held at the Alberta Hospital Edmonton, a psychiatric hospital.

“She's tormented by what she did,” Bottos said.

On Thursday and Friday, the defence is expected to bring in two forensic psychologists from Alberta Hospital to comment on Longridge's current mental health.

With a report from CTV Edmonton’s Shanelle Kaul