05/06/2013 02:13 pm ET

Noah Crooks Texted 'I Killed Mom Accidentally'; Accused Teen's Father Thought It Was A Joke

Disturbing details in the trial of Noah Crooks, an Iowa teen accused of the attempted sexual assault and murder of his mother in March 2012, came to light when the boy's father testified in court Friday.

An emotional William Crooks described his son's troubled relationship with his mother, Gretchen, as loving but marred by intense arguments and increasingly violent outbursts, ABC affiliate KAAL reported. According to the station, the father described incidents in which his son had stabbed sofa cushions and home fixtures with a knife, stating the boy often could not explain why he had acted out.

But the murder still came as a shock. According to the Waterloo-Cedar Falls Courier, William Crooks testified that he received a text message from his son the evening his wife was shot 20 times with a .22 caliber rifle. It read: "Dad this is Noah. I killed Mom accidentally. I regret it. Come home now please."

The boy's father thought it was a joke, and replied: "OK. Just throw her in the grove. We'll take care of her later."

911 recordings released earlier this month captured a chilling conversation between Noah Crooks and a dispatcher as the boy, who was 13 at the time, recounted how he shot and tried to rape his mother.

"I feel crazy and I know I'm not," the teen said on the 12-minute call, later adding, "I tried to rape her. I tried to rape her but I couldn't do it … I tried to rape my own mom. Who tries to rape their own mom? My life is down the drain now."

On May 1, sheriff's deputies testified that they had found the body of 37-year-old Gretchen Crooks at the family's Osage, Iowa, home, naked from the waist down. Her torso had been riddled with bullets.

According to the Des Moines Register, in testimony Friday, William Crooks said Gretchen had bought the weapon that may have killed her -- a Ruger hunting rifle -- for her son in 2010. William Crooks testified that the family had kept five guns in their home and said he had trained his son to use them, KIMT reports.

Noah Crooks' attorney does not dispute that the boy killed his mother, but he is pursuing an insanity defense. According to a separate KAAL report, in opening statements his attorney said he would call someone to testify that the accused teen suffers from intermittent explosive disorder, a behavioral disorder characterized by "repeated episodes of impulsive, aggressive [or] violent behavior," Mayo Clinic notes.

On May 4, witnesses who knew Noah Crooks from school testified that the boy had grown increasingly violent at school in the month leading up to his mother's death, according to the Waterloo-Cedar Falls Courier.

One witness, whose name was witheld at the request of the judge, testified that Noah Crooks had spoken of suicide the previous year. The witness also said the boy “got angry quicker... he’d get mad at things he wouldn’t usually get mad about.”



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