An 18-year-old Missouri resident received a life sentence Wednesday for the thrill killing of her 9-year-old neighbor, authorities said.

Alyssa Bustamante received a life sentence for the October 2009 death of Elizabeth K. Olten, according to the Cole County Circuit Court clerk's office in Jefferson City. She also got 30 years for armed criminal action.

Bustamante, who has the possibility of parole, allegedly told police she killed Olten because she wanted to know what it felt like to kill someone.

"These sentences are appropriate and fit what happened to Elizabeth at the hands of a truly evil individual who strangled and stabbed an innocent child simply for the thrill of it," Cole County prosecuting attorney Mark Richardson said in a statement.

Bustamante, wearing a bright green inmate's uniform, apologized to the Olten family in court, according to CNN Columbia affiliate KOMU.

"I know that words can never be enough, and they can never adequately describe how horrible I feel for all of this," Bustamante said. "I'm so sorry. If I could give my life to get her back, I would."

The judge ordered Bustamante, who entered a guilty plea in January, to serve her sentences consecutively. Bustamante was 15 at the time of the crime.

"Hundreds of law enforcement officers and regular citizens of Cole County searched for Elizabeth for two days and nights in the cold and pouring rain in October of 2009," according to Richardson. "The discovery of Elizabeth's mutilated body in a shallow grave is something that this entire community has been grieving for more than two years."

Defense attorneys told reporters that the sentence was "harsh" and that their client was not fully competent and suffers from depression, KOMU reported.

Bob Watson, media coordinator for Cole County Circuit Court, said a life sentence in Missouri equates to a maximum of 30 years on the charge of second-degree murder. Bustamante could serve a maximum of 60 years because of the consecutive sentence.