Woman breaks down before pleading guilty to stabbing teen cousin to death

Olivia Smith, then 18, killed her step-cousin, Abbey Hebert, an Allatoona High School student, outside a metro Atlanta home on Nov. 14, 2015.

According to the criminal warrant, Smith and Hebert smoked marijuana and then had an argument, which turned physical when Smith grabbed a kitchen knife and stabbed Hebert. Smith then chased Hebert outside the home, where witnesses described seeing the teen on top of Hebert, stabbing her multiple times.

Prosecutors and defense attorneys said Smith was in a drug-induced rage at the time.

"There's no way to sugarcoat it. It was a brutal murder, without a shadow of a doubt," Hebert's father, Steve Hebert, said. "When you brutally stab another person, go after their face, to dismember them in a way, it's a jealous rage."

Smith was charged with felony murder, malice murder, aggravated assault and possession of a knife during the commission of the crime.

As part of the plea deal to voluntary manslaughter, prosecutors asked the court to impose the maximum sentence of 20 years to serve.

"The amount of years, or whatever is spent in jail, is never gonna bring Abbey back," Steve Hebert said.

Smith cried in court as the prosecutor recounted the events of the day she killed Hebert.

Prosecutor Jesse Evans said on the day of the stabbing, Smith told police that she and Hebert had smoked something prior to the stabbing and "God told her to go after Abbey."

"There are no winners. There's only losers here and there's none greater than Abbey Hebert and her family," Evans said.

Tears flow during impact statements

During his victim impact statement, Steve Hebert spoke directly to Smith and her family in court, calling their actions appalling. Smith broke down once again and the judge had to stop Hebert to ask him to address the court and not individuals.

"None of us will be the same. It's not a grief that we live with on Nov. 14. It's a daily grief and we live with it every second of every day," Steve Hebert said.

Olivia Smith's sister, Hannah Smith, also gave a witness impact statement.

"I stand before you today to speak on behalf of my sister's character," Hannah Smith said. "My sister is not a monster. Olivia loved Abbey. She would do anything for her ... Olivia and Abbey were best friends. They were family."

Hannah Smith said drugs were to blame for what happened that day.

"Abbey would not want Olivia to be confined to a cell for the rest of her life," she said. "She would understand that drugs took over Olivia ... Drugs have destroyed our family and our lives forever."

Judge sentences woman to 20 years

After hearing the statements, the judge choked up as she sentenced Smith to 20 years in prison.

"There's two lives that are destroyed," she told the court. "Abbey will never be back, and you, Miss Smith, have to live with that. I do hope you think about this every day for the rest of your life."

The judge said Smith will get credit for time served. She then addressed Hebert's family and friends who believed the sentence should've been longer.

"Nothing can replace Miss Hebert, but that is the maximum I can do under the law," she said.

She also had a message for Smith's family.

"For those of you who think Miss Smith needs a lesser sentence, she made a choice and engaged in conduct and this was the result," she said.

WATCH the full court appearance on the WSB-TV Facebook page.