ROCHESTER HILLS, Mich. — A day before four students were killed at a Michigan school, the mother of the teenager charged with carrying out the mass shooting sent him a text message asking if he had showed teachers a “pic of your new gun,” an investigator testified Tuesday.

Jennifer and James Crumbley, the parents of Ethan Crumbley, the teenager accused of killing four students in a shooting at Oxford High School, appear in court for a preliminary examination on involuntary manslaughter charges in Rochester Hills, Mich., on Tuesday. Paul Sancya/Associated Press

The text was one of several between Jennifer and Ethan Crumbley on Nov. 29 after school officials left a voicemail informing her that the 15-year-old was looking up ammunition on his phone.

A judge must decide if there’s enough evidence to send Jennifer Crumbley and her husband, James Crumbley, to trial on involuntary manslaughter charges. It’s a low threshold under Michigan law, but this case is highly unusual because parents are rarely held criminally responsible for teens accused in mass school shootings.

The Crumbleys, who are in jail on $500,000 bond, are accused of making a gun accessible to Ethan and failing to intervene when he showed signs of mental distress at home and at school. Four students were killed and others were wounded in the Nov. 30 attack at Oxford High School, which is roughly 30 miles north of Detroit.

The school left a voicemail for Jennifer Crumbley the day before the attack informing her that a teacher was concerned about Ethan’s ammunition search on his phone.

In court, Ed Wagrowski, a computer crimes investigator in the Oakland County sheriff’s office, read aloud a series of texts exchanged between mother and son.

“Seriously?? Looking up bullets in school??” Jennifer Crumbley wrote.

Her son replied: “Oh yeah. I already went to the office for that. All I did was look up a certain caliber at the end of class because I was curious. Completely harmless.”

“Did you at least show them a pic of your new gun?” Jennifer Crumbley asked.

“No I didn’t show them a pic. My God,” he wrote back.

The Crumbleys’ attorneys insist the couple didn’t know their son might be planning an attack and that they didn’t make the gun easy to find in their home.

Prosecutor Karen McDonald said she was trying to show that the Crumbleys committed gross negligence. Her first witness was the manager of a stable where the couple kept two horses and visited three to four times a week.

McDonald’s questions were intended to show that the parents seemed more concerned about the health of a horse that had a leg fungus than the “disturbed” mental health of their son.

Wagrowski read aloud text messages written by Ethan to his mother last March. The teen said their house was haunted and a demon was throwing bowls. Jennifer Crumbley was riding a horse and didn’t respond that day, the investigator said.

On the morning of the shooting, Jennifer and James Crumbley were summoned to the school and confronted with Ethan’s drawings, which included a handgun and the words, “The thoughts won’t stop. Help me.” Authorities said the parents refused to take him home after the 13-minute meeting and were told to get him counseling.

Amanda Holland, a co-worker at a real estate company, said Jennifer Crumbley shared a picture of the drawings when she returned to work from the school meeting.

“I told her I thought it was scary. She agreed,” Holland testified.

“I said it would be nice for her to take him for a day, go see a movie, go have lunch,” Holland said. “I said she should have brought him home. I thought it was a disturbing photo and this child needed to be around family.”

Jennifer Crumbley said “she felt like a failure as a parent,” according to Holland, who added that it seemed a “little sarcastic.”

Jennifer Crumbley’s boss, Andrew Smith, said she shared an image of the drawings with him, too, though he didn’t immediately look at it.

“She had said her son needed to get some counseling,” Smith testified. “I think she mentioned a family pet had passed away and a grandparent had passed away. She felt as if she was failing him, or a failure.”

By late afternoon, after the shooting, Jennifer Crumbley expressed concern about losing her job, Smith said.

“’Please don’t judge me for what my son did.’ I was surprised by that text,” Smith told the court. “I was surprised she was worried about her job at that time.”

Ethan Crumbley is charged as an adult with murder and other crimes. His lawyers filed a notice of an insanity defense, which will likely freeze his case while experts examine him.

There wasn’t much focus Tuesday on James Crumbley, although his distressed voice filled the courtroom when prosecutors played a 911 call from after the shooting. He reported that a gun was missing from home and his son was an Oxford student.

Defense attorney Shannon Smith dabbed Jennifer Crumbley’s teary eyes with a tissue. She couldn’t do it herself because of restraints on her wrists.

The hearing will resume with more testimony on Feb. 24.