Kimberly Cates Update: Trial begins for N.H. home invasion killer claiming insanity

(CBS/AP) NASHUA, N.H. - A prosecutor says 21-year-old Christopher Gribble, who claims he was insane when he helped kill a New Hampshire mother and injure her daughter, "chose to be a murderer and not a madman."

Prosecutor Jeffery Strelzin made the comments during Thursday's opening statements in Gribble's trial. He has acknowledged his role in the October 2009 attack that killed Kimberly Cates and injured her daughter Jaimie, but he claims he was insane.

Gribble's attorney told the jury in his opening statement that his client had been diagnosed with personality disorders and sociopathic characteristics. Attorney Matthew Hill called it "a very grim diagnosis."

If Gribble is found insane and dangerous, he would be committed to the secure psychiatric unit of the state prison and his case would be reviewed every five years.

Another defendant, Steven Spader, was convicted in November and sentenced to life in prison for his role in the attacks.

Click here for complete coverage of the Kimberly Cates case on Crimesider