(CBS/AP) JEFFERSON CITY, Mo. - A Missouri teenager who told authorities that she strangled, cut and stabbed a 9-year-old neighbor because she wanted to know how it felt pleaded guilty Tuesday in the girl's death.
Alyssa Bustamante pleaded guilty to second-degree murder and armed criminal action in the Oct. 21, 2009, killing of Elizabeth Olten in St. Martins, a rural town just west of Jefferson City.
Bustamante, who will turn 18 on Jan. 28, told Judge Pat Joyce that she knew what she was doing at the time.
Bustamante admitted she used a knife to cut Elizabeth's throat and then strangled the girl with her hands. The confession prompted a sharp, audible intake of breath from Elizabeth's tearful mother who sat in the courtroom just a few feet away.
Bustamante, who was 15-years-old at the time of the attack, had been charged with first-degree murder and was supposed to stand trial starting Jan. 30.
Instead, sentencing was set for Feb. 6.
The plea deal does not include any agreement on a possible sentence. Bustamante could face between 10-30 years to life in prison for the murder charge, and three years to life for armed criminal action.
At a November 2009 hearing, prosecutors said Bustamante plotted Elizabeth's death, even digging two holes to be used as graves, then attended school for about a week while waiting for the right time to kill. They said Bustamante strangled Elizabeth without provocation, cut the girl's throat and stabbed her.
Missouri State Highway Patrol Sgt. David Rice testified that the teenager confessed to the slaying and led authorities to Elizabeth's body. Rice said Bustamante told him "she wanted to know what it felt like" to kill someone.
Hundreds of volunteers searched for two days for Elizabeth before her body was found.
Juvenile justice officials testified that Bustamante had attempted to commit suicide in 2007 and had been receiving mental health treatment for depression and cutting herself.
Witnesses at Bustamante's adult certification hearing described her as a bright girl who ranked roughly in the top third of her class at Jefferson City High School. She had not been in trouble at school or with the law before her arrest in Elizabeth's killing.