A Vermont man charged with killing Catherine "Kitty" Houghton of Novato at a New Hampshire hotel earlier this year has indicated he will invoke a defense of not guilty by reason of insanity.

Rodney Hill, 37, was indicted in June for second-degree manslaughter in the stabbing death of 70-year-old Houghton in the lobby of the Hampton Inn in Littleton on Jan. 28.

Houghton had traveled to New Hampshire for a board of trustees meeting at White Mountain School in Bethlehem. She was a 1960 graduate of the school. She had remained an extra day in New Hampshire to rehearse with her alma mater's a capella choir, school officials said.

Hill's lawyers have requested a hearing regarding notice of the defendant's intent to enter the insanity plea, according to court documents. A competency hearing for Hill is scheduled for Nov. 14, according to the Caledonian Record of New Hampshire.

Before retiring, Houghton was a business counselor with the U.S. Foreign Service. She was a member of the Choral Singers of Marin, a member and membership chairwoman for the Marin chapter of the Ninety-Nines -- an international organization of women pilots -- a board member of the Indian Valley Associates homeowners association, and a volunteer for Angelflight.

Hill told police he was going through a divorce and was angry at an email he had gotten from his boss when he punched and stabbed Houghton. Prosecutors said the two did not know one another and the attack appeared to be random. Hill had checked into the hotel earlier in the day.

According to the autopsy report, Houghton died of a stab wound to the neck.

The arrest affidavit states that a hotel manager saw Hill tackle Houghton from behind and then heard Houghton screaming. The hotel manager, Erica Green, said she told Hill to stop as she was calling 911. Hill calmly walked toward her.

"Hill then began talking to Green about an apocalypse, that he was the salvation and stated something about smartphones," according to the affidavit.

Hill told police his father was Lucifer, and blamed him for Hill's inability to send an email response to his boss or make a phone call.

He told police he "underwent a Biblical experience, wherein he thought he was Jesus due to the sacrifices he had made, and that his father was the devil and out to ruin his family," the affidavit states. "He believed his father, as the devil, would appear in a different form that he would not recognize."

Contact Megan Hansen via email at mhansen@marinij.com or via Twitter at http://twitter.com/hansenmegan. Follow her blog at http://blogs.marinij.com/bureaucratsandbaking.

The Associated Press contributed to this report.