(CBS/AP) JEFFERSON CITY, Mo. - Missouri teenager Alyssa Bustamante has been sentenced to life in prison with the possibility of parole in the killing of a 9-year-old girl.
The 18-year-old was sentenced Wednesday in Cole Country Circuit Court. She pleaded guilty in January to second-degree murder and armed criminal action in the October 2009 stabbing and strangling of her neighbor, Elizabeth Olten.
Bustamante's defense attorneys said in court that an abundance of the drug Prozac could have been a catalyst to her behavior. A consulting psychiatrist testified Monday afternoon that Bustamante's prescription for Prozac may have helped lead her to kill.
Missouri's News Tribune reports Dr. Edwin Johnstone told Cole County Circuit Judge Patricia Joyce that Prozac and several similar drugs were "showing an abundance of suicides and violent events, including homicides," he said.
Johnstone also testified that Bustamante received several different dosages of the drug over a two-year period -- including an increase to a higher dosage than ever before, only two weeks before the murder.
Prosecutor Mark Richardson noted the FDA never has determined that Prozac cause people to kill.
Law enforcement officers, attorneys and forensics experts read aloud the journal entries written by Bustamante when she was a 15-year-old high school sophomore.
The now 18-year-old wrote on the night of Elizabeth's murder:
"I just f------ killed someone. I strangled them and slit their throat and stabbed them now they're dead. I don't know how to feel atm. It was ahmazing. As soon as you get over the "ohmygawd I can't do this" feeling, it's pretty enjoyable. I'm kinda nervous and shaky though right now. Kay, I gotta go to church now...lol."
Bustamante, who was 15 at the time, had been charged with first-degree murder. However, by pleading guilty to the lesser charges, she avoided a trial and the possibility of spending her life in adult prison with no chance of release.