Defence lawyers argued in court that a Victoria woman accused of killing her 18-month-old daughter was suffering from a mental disorder when it happened.

The first-degree murder trial for Kaela Mehl continued in an emotional day at court as the defence mounted its case Thursday.

In front of a jury, a forensic psychiatrist testified he believed the 34-year-old woman was suffering from adjustment disorder when she fed her daughter Charlotte sleeping pills mixed with yogurt before smothering her on Sept. 16, 2015.

He also said Mehl killed her daughter in an act of what’s called altruistic filicide, meaning she believed she was protecting the baby from perceived threats posed by Mehl’s father-in-law and neglect from the child’s father.

Mehl has pleaded not guilty in the death, but her defence doesn’t deny that she killed her daughter.

Mehl’s ex-husband was in court Thursday and was visibly shaking as he fought back tears.

Mehl herself was sobbing at various times throughout the testimony, including when the doctor described a distraught Mehl clutching her daughter’s toys close to her chest as she talked about her.

Crown has previously argued that Mehl intentionally and deliberately killed her daughter.

The trial is expected to last for one more week.