VANCOUVER -- Warning: Disturbing content.

A trial is now underway for a Langley, B.C., woman accused of killing her seven-year-old daughter in 2018.

Kerry Ann Lewis is charged with first-degree murder in the death of Aaliyah Rosa, whose body was found in an apartment on July 22 of that year.

None of the allegations have been proven in court.

In an opening statement Monday, prosecutor Kristen LeNoble told the court the Crown will argue Lewis had been planning to kill her young daughter before the two of them arrived at the apartment that day.

"The Crown intends to prove that Ms. Lewis killed Aaliyah Rosa, that she intended to do so, and that the murder was planned and deliberate," said LeNoble.

She told the court they will argue Lewis sedated Aaliyah and then drowned her in a bathtub.

LeNoble said the court will hear that Lewis picked Aaliyah at the Langley Events Centre, where Aaliyah was brought by her father, Stephen Rosa, for one of her two scheduled weekly visits.

The Crown said Lewis and Rosa had separated in 2016, and Rosa had custody of his daughter.

"Your ladyship will hear that custody and access of Aaliyah, the only child of Ms. Lewis and Mr. Rosa, was particularly contentious, and that the accused was frustrated that her visits with Aaliyah were limited to twice a week with no overnights," LeNoble told the judge.

LeNoble told the court that Lewis had been in an argument with her then-boyfriend the night before Aaliyah's death.

The boyfriend texted Lewis the next morning and told her their relationship was over, and he would be returning with friends later in the day to get his things from the apartment, LeNoble said.

Before picking up Aaliyah, the Crown told the court, Lewis made two short phone calls to a Shoppers Drug Mart, which she visited with her daughter later that morning.

LeNoble told the court Lewis purchased an over-the-counter box of sleeping pills, candy and a bottle of blue Powerade. The Crown said she also refilled a prescription for an emergency supply of Ativan, a medication often used to treat anxiety disorders, seizures, withdrawal and other conditions.

LeNoble said Lewis also went to a liquor store and bought a bottle of vodka. The Crown said her building key fob was used to enter the apartment's parkade gate at 11:38 a.m.

"That was the last time that day that the key fob ordinarily used by the accused was used to enter or exit the building," LeNoble said.

The prosecutor told the court after that point Lewis did not send any messages or make calls on her phone for the rest of the day.

LeNoble said Aaliyah was not returned to her father at 5 p.m. He returned to their appointed meeting place at the events centre again at 7 p.m., and then called police to report his daughter had not been returned as scheduled and he was afraid for her safety.

The Crown said Lewis's ex-boyfriend and two friends arrived the apartment at about 9 p.m.

She said they found the front door blocked with boxes and furniture, but were able to get inside.

LeNoble told the court Aaliyah's body was found on the floor of the ensuite bathroom.

She told the court the little girl was cold and wet, and was wrapped in a pink bathrobe. At that point, a 911 call was made, LeNoble said.

She told the court the accused was found face down in the bathtub, which had water in it. She was treated and taken to hospital.

"The evidence will also show that since 2010, Ms. Lewis has been admitted to hospital on several occasions as the result of apparent suicide attempts through overdoses of prescription medication," LeNoble said.

Aaliyah's family members were in the courtroom for the start of the trial, which is scheduled to take 22 days. Her father is expected to testify later in the proceedings.

Before the Crown's opening statement, Lewis was asked how she intended to plead. She responded: "Not guilty."

Lewis was arrested and charged with second-degree murder in August 2018. That charge was later upgraded in early 2019.

Their first witness on Monday was an RCMP officer who was called to take photographs of the apartment.

The Crown is expecting to call a number of people to testify, including emergency responders, people who formerly lived with Lewis, and the sister of the accused.