A 15-year-old Missouri girl pleaded not guilty Tuesday to killing a 9-year-old neighbor girl, who authorities say was murdered because the teen wanted to know what it felt like to kill someone.

Alyssa Bustamante sat silently as an attorney entered a not guilty plea on her behalf to first-degree murder and armed criminal action in the Oct. 21 death of Elizabeth Olten.

Bustamante often gazed down — her long bangs covering her eyes, her hands and feet shackled — during a Cole County court hearing that lasted less than a minute.

Authorities say Bustamante plotted Elizabeth's slaying — digging two holes several days in advance — then strangled her without provocation, cut the girl's throat and stabbed her.

They say Bustamante led officers to Elizabeth's body in a wooded area near the girls' homes after hundreds of volunteers helped in a two-day search for the missing fourth-grader.

The girls lived several houses apart in St. Martins, a small town just west of Jefferson City.

During a court hearing last month, Missouri State Highway Patrol Sgt. David Rice testified that Bustamante had confessed to the killing to investigators. "Ultimately, she stated she wanted to know what it felt like," Rice said.

Bustamante was certified last month to stand trial as an adult. Her arraignment Tuesday was necessary because Bustamante did not have an attorney during her initial Nov. 18 hearing, when Cole County Circuit Judge Patricia Joyce entered a not guilty plea on her behalf.

The hearing Tuesday also marked the first time that cameras and recorders were allowed in the courtroom for proceedings in the case.

Juvenile justice officials testified last month that Bustamante had been receiving mental health treatment because of a history of depression and had tried to kill herself about two years ago.

Her public defender, Jan King, asked the court to transfer her from jail to a state psychiatric hospital for a four-day evaluation because of depression. But the judge has not ruled on the request, and King said he did not want to take it up for consideration during Tuesday's court appearance.

The judge scheduled a Feb. 16 hearing for an update on Bustamante's case.