POMONA (AP) — A woman charged with stabbing to death a romantic rival has pleaded not guilty by reason of insanity.

Pomona Superior Court Commissioner Wade Olson warned 34-year-old Nicole Ann Stewart on Wednesday that her plea means she could spend the rest of her life in a mental institution. He appointed two psychiatrists to interview her and submit reports by an Oct. 26 hearing.

The Inland Valley Daily Bulletin says Stewart is accused of using a kitchen knife to kill 49-year-old Robin Ridgeway on July 23, 2009.

Investigators say Ridgeway falsely believed Ridgeway was romantically involved with Stewart's boyfriend.

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