Alyssa Bustamante
Alyssa Bustamante pleaded guilty to one count of second-degree murder after strangling, stabbing and slitting the throat of her 9-year-old neighbor Elizabeth Olten. The Missouri 18-year-old, who was 15 at the time of the murder, was sentenced to life in prison with possibility of parole on Wednesday.Dr. Edwin Johnstone, a consulting psychiatrist who testified on Bustamante's behalf in court, said that changes in her Prozac prescription could have played a part in mood swings that may have contributed to Bustamante's murderous tendencies. People who were prescribed Prozac "were showing an abundance of suicides and violent events, including homicides,” Johnstone told the court.

A depressed teenager was sentenced to life for the murder of her nine-year-old neighbour in Missouri.

Alyssa Bustamante admitted strangling, stabbing and slitting the throat of her sister's friend, Elizabeth Olten, in St Martins, Missouri, a small town west of Jefferson City.

Bustamante was just 15 at the time of the murder on 21 October, 2009.

The story took another sickening twist when excerpts of her diary were read out in court. In the diary, she called the murder experience "ahmazing".

She wrote: "I just f***ing killed someone. I strangled them and slit their throat and stabbed them now they're dead. I don't know how to feel atm [at the moment].

"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"

Bustamante, now 18, came face to face with the mother of her victim before she was sentenced.

"I know words can never be enough and they can never adequately describe how horribly I feel for all of this," Bustamente said.

"If I could give my life to get her back I would. I'm sorry."

The Missouri teenager's defence argued that her use of the antidepressant Prozac had made her violent and that she had suffered with depression for a long time.

They also claimed she had attempted suicide by overdosing on painkillers in an effort to be granted leniency.

But prosecutors noted that Bustamante had dug two graves several days in advance.

Missouri State Highway Patrol Sgt David Rice testified that Bustamante showed police where she had buried her victim and admitted to the killing because "she wanted to know what it was like to kill".

Olten's family called for the defendant to receive the maxium penalty. She had pleaded guilty in January to second-degree murder and armed criminal action.

Cole county circuit judge Patricia Joyce sentenced her to life, with the possibility of parole, for second-degree murder, plus 30 years for the second charge.