Amanda Greene has pleaded guilty to manslaughter in the shooting death of ex-boyfriend Dillon Jewett last fall.
Greene, 19, was charged with first-degree murder, but she pleaded guilty to the lesser charge Thursday in Nova Scotia Supreme Court.
Jewett, 18, was found dead in a quarry near East Uniacke on Oct. 3, 2010.
Kyle Gowen, Greene's boyfriend at the time, has already been sentenced to life in prison for second-degree murder. He admitted to shooting Jewett in the head, first accidentally and then twice more.
Brian Smith, Greene's lawyer, said his client took responsibility for her part in the killing by pleading guilty to manslaughter.
Crown attorney Alison Brown said she was satisfied with the plea.
"Based upon the evidence we do have, our understanding of case law and a thorough review of that evidence, manslaughter was an appropriate charge," she told reporters outside the courtroom.
First-degree murder involves planning and the intention to kill, while manslaughter is the unlawful causing of a death.
Both Brown and Smith refused to comment on Greene's involvement. The details will come out when the young woman is sentenced on Oct. 25.
Greene, who has been out on bail, was calm as she answered the judge's queries about whether she understood the consequences of her guilty plea.
Smith said the sentence for manslaughter ranges from probation to life in prison.
He said it's been a stressful time for Greene, her family and Jewett's family.
"It's not an easy thing to be charged with first-degree murder and not easy to sit at home wondering how this is going to come out, where you're going to be spending perhaps a significant part of your future life," he said.
Kyle Gowen, 23, will be eligible for parole after 15 years.
Steven Gowen, Kyle's 21-year-old brother, pleaded guilty to accessory to murder after the fact. He was sentenced to three years in prison, minus eight months for time served.
James William Patterson, 21, still faces a charge of accessory.