The Denair teenager facing charges for the killing of her father and stabbing of her mother, has changed her not guilty plea to one of not guilty by reason of insanity.

Shanna Wills, 19, is facing charges of murder, attempted murder, and assault with a deadly weapon from the May 8, 2011 attack that left her father, Kenneth Wills, 62, dead and her mother, Susan Wills, hospitalized.

The change in the plea prompted Stanislaus County Superior Court Judge John D. Freeland to assign two doctors to the case. The two doctors will evaluate Wills separately and submit their findings on her mental health. She is due in court again on July 29.

During her preliminary hearing last year, Wills’ attorney Deputy Public Defender Greg Speiring didn’t call any witnesses to the stand, but did say that Wills’ “conduct was a product of her mental disease,” in his closing statement.

At the time, Freeland said he couldn’t make any judgments about Wills’ mental state because no expert testimony had been given.

Even though no expert testimony was given during the preliminary hearing, there was plenty of testimony given about the bizarre events of that day.

Wills was preparing an elaborate Mother’s Day celebration at the Denair home on Salluce Drive. A male teenage friend of Wills testified at the preliminary hearing that he came to the house and found cut flowers in every vase, jar, cup and container in the house.

He said Wills was spreading rose petals on the floor and preparing dishes her mother liked to eat.

The 17-year-old testified Kenneth Wills walked into the kitchen and seeing the display started yelling and cussing at Wills.

Susan Wills testified at the preliminary hearing that she arrived home around 6:30 p.m. and found her husband and daughter engaged in a verbal onslaught with one another. Susan Wills testified that the dispute turned physical when Wills used a shard from a broken horse statue to slice her father’s forehead. Kenneth Wills went into the kitchen, at which point Wills allegedly hit him with a vacuum and a stand-up electric fan.

According to the prosecution, Susan Wills and her husband were forced into their bedroom by Wills. Susan Wills recalled Wills ordering them to beg for forgiveness and telling them that they wouldn’t be hurt because she had made them angels.

Susan Wills said she was stabbed in the back by her daughter with a decorative knife Wills had picked up during the altercation. The wound punctured Susan Wills’ lung.

The fight between Kenneth Wills and Wills continued until he lay motionless in the hallway. Forensic pathologist Sung-Ook Baik testified that Kenneth Wills sustained six stab wounds and numerous bruises from blunt force traumas. Baik said all the stab wounds but one were superficial. The one fatal wound pierced Kenneth Wills’ intestine. Baik said Kenneth Wills died from blood loss that occurred over 20 to 30 minutes.

The first Stanislaus County Sheriff’s deputies to arrive at the home found Wills in a semi-stupor sitting nude in an overflowing tub.

Deputy Nathan Malone took Wills to the sheriff’s department and he testified at the preliminary hearing that Wills said, “I was planning this. I had to do it.”

Sheriff’s Detective Frank Soria interviewed Wills for about three hours and during that time she continually referred to herself as God, the female Jesus, and that she had been sent to rid her parents of their sins.

At some points in the interview Wills, who had been clothed in a disposable haz-mat suit, would pull the hood tight over her face and rock in a corner.

During the interview Soria gave Wills a bottle of water and then left the room. Via the video monitor he saw Wills pour the water onto his seat. Soria recounted that when he returned to the room Wills told him it was her blessing to him and that he would not get wet.

Soria described Wills as having erratic mood shifts going from giggles to sobs. She would also speak to him in an altered voice that she claimed was God.

A blood test on Wills was negative for alcohol, methamphetamine and cocaine and was positive for marijuana, according to court testimony.

Three days prior to the attack, Wills was found wandering outside a rural Denair home. Homeowner Ray Mendonca testified at the preliminary hearing that Wills told him she had gotten into a stranger’s car and been dropped off there. Mendonca said Wills seemed confused and scared.

To find an insanity plea valid it has to be determined that because of a mental defect or disease a person did not know or understand the nature of his or her actions, or could not distinguish between right or wrong at the time of the act.

Wills remains in custody at the Stanislaus County Jail.