A woman who killed her eight-year-old daughter to spite her ex-husband was sentenced to life in prison Tuesday without the possibility of parole for 15 years.

In sentencing Lisa Batstone for the second-degree murder of her daughter Teagan — who was found dead in the back of Batstone's car on Dec. 10, 2014 — New Westminster Supreme Court Justice Catherine Murray said the court needed to send a strong message to warring parents who would use their children as weapons.

"The breach of trust could not be more abhorrent," Murray said.

"Children are not to be used as pawns in matrimonial or personal disputes."

Murray convicted Batstone in March. Second-degree murder carries an automatic life sentence, but parole eligibility can range from 10 to 25 years.

Crown had asked for a parole ineligibility of between 16 and 18 years. But the defence had argued that Batstone's mental issues warranted a period of 10 years.

Murray found that the case met the bar for a harsher sentence: "egregious circumstances of higher order of moral culpability."

Teagan Batstone was found dead on Dec. 10, 2014. (Gabe Batstone)

'I hope you will all at some point find peace'

Batstone sobbed and groaned from the prisoner's dock as Murray relayed the circumstances of the case to the courtroom, starting with a personal address to the crowd of family and friends who have attended the proceedings.

"To describe Teagan's death as tragic is an understatement," she said. "Teagan's death has clearly left a hole that will never be filled. That she was taken from all who loved her very much is devastating."

Murray said that no sentence could ever bring Teagan back.

"I hope you will all at some point find peace in the memories of your beautiful girl."

Batstone's lawyers claimed she had been diagnosed with borderline personality disorder in jail and was suffering from anxiety at the time of the murder. But the judge said those factors didn't take away from her moral culpability in planning and committing the most extreme breach of trust imaginable for a parent.

And her goal throughout was to hurt Teagan's father — her ex-husband Gabe Batstone.

Gabe Batstone and his daughter Teagan in a photo before she was found dead in December 2014. (Gabe Batstone)

Murray said Batstone planned to kill herself and to kill Teagan as a way of making sure that Gabe Batstone couldn't have the child after she was dead.

The judge said Batstone, who was 41 at the time of the murder, never wavered. At her South Surrey home, she held a heavy plastic bag over the child's nose and mouth for four to five minutes to ensure her death.

Lisa Batstone then tried to kill herself using two smaller plastic bags, but couldn't go through with it. She left notes in her home that said, "You win Gabe," and, "You broke me."

Failing to kill herself, she ultimately placed her child's body into the trunk of her car and left home. She was carrying a large kitchen knife. Her car ran off the road in Surrey and she asked a stranger to call 911.

She was found in the trunk of her car, cradling Teagan's body.

Murray found that Batstone had lied after her arrest about the extent of her mental illness in a bid to be found not criminally responsible for the murder.

Lisa Batstone being interviewed by Const. Emilie Tousignant of the RCMP after she was arrested in the death of her daughter, Teagan. The whole interview lasted two hours. (RCMP )

She also said she was in no doubt that Batstone loved Teagan.

But she refused to accept the defence's contention that Batstone's sorrow over her actions should mitigate against the length of her sentence.

"In my view, loving someone does not render murdering them less serious," Murray said.

"Her mother was her safety net. Her mother was her protector."