An attorney for a Colorado woman accused of stabbing her 11-year-old stepson 18 times before shooting him in the head and eventually dumping his body in Florida while claiming the boy had gone missing cited a "major psychotic crack" Monday in justifying why she changed her plea to not guilty by reason of insanity. 

Letecia Stauch is accused of killing 11-year-old Gannon Stauch in his bedroom a few hours before reporting him missing Jan. 27, 2020, while his father was on a National Guard deployment. Her arrest affidavit cites internet searches suggesting she was unhappy in her marriage and resentful of being treated like an unpaid babysitter.

At the start of her trial Monday, a prosecutor told jurors Letecia Stauch knew "she could determine right from wrong."

"Gannon suffered 18 stab wounds to his body, his chest, his back, his head, and most importantly, his arms and his hands. Why is that important? He was fighting for his life. And those were defensive wounds," District Attorney Michael Allen said, according to WPDE.

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"She carried out actions to kill and put his body in a suitcase and hide it to hide evidence of what she did, to give numerous stories to investigators, to manipulate the course of the investigation, and finally to discard Gannon inside that suitcase, off a Florida bridge like garbage." 

Letecia Stauch mugshot

Letecia Stauch is accused of murdering her 11-year-old stepson.  (El Paso County Sheriff's Office via AP, File)

Defense lawyer Will Cook told the jury of 11 men and seven women Monday that Stauch suffered a "major psychotic crack" as a result of past abuse when she was a child. 

Cook said she was physically, emotionally and sexually abused at the hands of her mother’s boyfriends beginning at the age of 3 or 4, KMGH-TV reported. 

"She witnessed her mother get abused until eventually the abuse her mother endured was transferred onto her," Cook said. "It started as physical beatings and turned into sexual assault later." The attorney claimed she slipped into a "dissociative" state and "broke," believing she "was killing the demons in her life, in the dark depths of her childhood."

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After allegedly stabbing the boy repeatedly, Stauch then grabbed a handgun and fired three times at Gannon, striking him once in the head, prosecutors said Monday, according to KUSA. 

"She gathered his bloody and broken body and stuffed him into a suitcase and stored his body in the basement storage room," Allen said.

The district attorney said Stauch then took the suitcase containing her stepson's body, loaded it into a rented vehicle and took it with her as she traveled to her hometown in South Carolina. Stauch allegedly tossed the suitcase off a bridge in the Florida Panhandle, Allen said, where a bridge worker discovered the body about six weeks later. 

Gannon Stauch school photo

Authorities spent weeks searching for 11-year-old Gannon Stauch before his stepmother was arrested and his body was found in Florida. (El Paso County Sheriff's Office)

Initially, authorities said they responded after Stauch said Gannon had not returned from playing with a friend. But she did not provide the names of any friends he may have been with or their parents. Within days, she concocted a variety of stories to mislead them, including that a man she hired to repair a carpet raped her and then abducted Gannon, investigators say. 

More than 200 volunteers conducted searches for the boy in the area where the family lived near Colorado Springs as authorities investigated. 

About two weeks after Gannon disappeared, searchers found a piece of particle board with Gannon's blood on it in a rural area nearby. Presuming the boy to be dead, authorities arrested Stauch in Myrtle Beach March 2, 2022. Gannon's remains were found later that month in the small city of Pace in northwestern Florida. 

Gannon Stauch smiles wearing beanie

Gannon Stauch was allegedly killed by his stepmother in January 2020.  (El Paso County Sheriff's Office)

In his opening, Allen said the boy, who was born premature, "proved to be a fighter," reportedly prompting his mother, Landon Hiott, to run from the courtroom overcome with emotion. 

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Stauch was charged with first-degree murder, tampering with a deceased human body and tampering with physical evidence. 

After her arrest, she was also accused of trying to escape from jail. Court documents allege she asked a fellow inmate to help her get out, explaining she planned to use a broom handle to break the window in her cell and that she had already measured herself to make sure she could fit through.

The Associated Press contributed to this report.