Crooks let his father know through a text message that said, "Dad this is Noah. I killed Mom accidentally. I regret it. Come home now please," according to a report by the NY Daily News.
His father, William Crooks, thought the text was a joke -- and responded with, "OK. Just throw her in the grove. We'll take care of her later."
On Wednesday in court, prosecutors played all 10 minutes of Noah's 911 call, in which he admits to shooting his mother more than 20 times. He also admitted to trying to rape her.
When Mitchell County police arrived at their Osage, Iowa home, 37-year-old Gretchen Crooks was nearly naked. Her torso was riddled with 15 bullets. The State Medical Examiner's office found those, along with two more bullets in her head and four in her neck.
"I'm not joking at all. She's dead. I'm scared," Noah Crooks said in the 911 call. "I killed my mom with my .22. I don't know why I did it," according to a report by the Mason City Globe Gazette.
Noah also told the dispatcher that his mother took away the shooting video game "Call of Duty" after he came home with bad grades. Defense attorney William Kutmus said Gretchen Crooks had taken the video game controller about three hours before the murder, potentially leading to the shooting.
Students testified Wednesday that Noah Crooks had sometimes been violent in school, and would stab students with pencils and threaten to kill them. He had threatened to kill his mother before, one of the students said.
Testimony continues today in Wright County District Court in Clarion, Iowa. A child psychiatrist is expected to testify that Crooks suffers from a behavioral disorder that causes episodes of impulsive, aggressive or violent behavior.