FREDERICK, Md. (AP) — A Frederick County woman is pursuing a mental-illness defense in the fatal stabbing of her grandmother last December.

Twenty-year-old Hestina Harris pleaded not guilty and not criminally responsible at a court appearance Monday in Frederick. She is charged with first-degree murder in the Dec. 22 slaying of 67-year-old Lillie Morris at their home near Burkittsville.

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Harris’ public defender says he’s awaiting results of a psychiatric evaluation of his client. She was found competent in January to participate in her defense.

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Prosecutors say Morris was stabbed or cut 23 times with a kitchen knife. She was found dying on her front lawn.

Harris previously denied killing Morris. She told investigators she saw a masked man running from the house shortly after the attack.

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