Authorities are searching for the parents of a teenager accused of killing four people in a Michigan high school shooting earlier this week, the sheriff’s office confirmed Friday.

The news came shortly after Oakland County Prosecutor Karen McDonald announced that James and Jennifer Crumbley had been charged with four counts of involuntary manslaughter.

“While the shooter was the one who entered the high school and pulled the trigger, there are other individuals who contributed to the events on Nov. 30, and it’s my intent to hold them accountable as well,” McDonald said at a news conference.

She added, “Gun ownership is a right, and with that right comes great responsibility.”

The U.S. Marshal Service is involved in the search for the parents. The agency did not immediately return a request for comment on Friday.

James Crumbley purchased the weapon days before the shooting, according to the sheriff. McDonald told reporters that James Crumbley brought the suspect, Ethan Crumbley, with him to the store.

Under Michigan law, an involuntary manslaughter charge can be pursued if prosecutors believe someone contributed to a situation in which harm or death was high. If convicted, they could face up to 15 years in prison.

Ethan Crumbley, 15, has been charged as an adult with two dozen crimes, including murder, attempted murder and terrorism, in the shooting Tuesday at Oxford High School in Oakland County, roughly 30 miles north of Detroit.

In an appearance on NBC News NOW, Oakland County Sheriff Michael Bouchard said Thursday that it is “clearly a crime” if someone gives a firearm to a minor.

In a separate appearance on MSNBC, the top prosecutor in Oakland County said Thursday that the teen appeared to have “free access” to the gun.

“If you own a weapon or possess a weapon and you knowingly allow someone to have free access to it, who you have reason to believe might use it to injure somebody, that is willful and it’s gross negligence, and there are lots of criminal consequences for that,” McDonald previously said.

During Friday’s news conference, she said that a teacher had observed Ethan Crumbley searching ammunition on his cellphone and alerted school officials. The school tried to contact his mother but could not reach her.

McDonald told reporters that Jennifer Crumbley did not contact the school but instead texted her son: “Lol. I’m not mad at you. You have to learn not to get caught.”

On Tuesday, prior to the shooting, another teacher alerted school officials to a drawing the teacher found on Ethan Crumbley’s desk. It contained a drawing of a gun pointing at the words “the thoughts won’t stop, help me,” the prosecutor said.

There was also a drawing of a bullet with the words “blood everywhere” written above it and a drawing of a person who appeared to have been shot twice and was bleeding. McDonald said the drawing of the person included a laughing emoji and the phrases “my life is useless” and “the world is dead.”

After the teacher found the drawing, Ethan Crumbley was removed from class and his parents were asked to come down to the school immediately. A counselor showed the parents the drawing but Ethan Crumbley had already altered it and scratched out some of the images and words, according to McDonald.

The parents were told they needed to get Ethan Crumbley into counseling within 48 hours, McDonald said.

“James and Jennifer Crumbley resisted the idea of their son leaving the school at that time,” she said. “Instead, James and Jennifer Crumbley left the high school without their son. He was returned to the high school.” 

The prosecutor told reporters that the teen should not have been allowed to return to the classroom.

The shooting happened just before 1 p.m. McDonald said that after news broke that there was an active shooter at the high school, Jennifer Crumbley texted her son at 1:22 p.m., “Ethan, don’t do it.”

Around 1:37 p.m., James Crumbley realized the gun — which was kept in an unlocked drawer in their bedroom — was missing and called police to say that he thought his son might be the shooter, according to McDonald.

The Crumbleys have not cooperated with authorities, nor have they given their son permission to talk with investigators, as is required for minors in Michigan, the county sheriff said.

“There’s no conversation occurring between us, the suspect or the parents,” Bouchard told NBC News Now on Thursday.

A message left on a phone number listed under James Crumbley’s name was not returned. A lawyer who represented Ethan Crumbley at his arraignment, Scott Kozak, did not respond to a request for comment.

Ethan Crumbley has been charged as an adult with four counts of first-degree murder, one count of terrorism causing death, seven counts of assault with intent to murder, and 12 counts of possession of a firearm in the commission of a felony.

Authorities have identified the four students who were killed as Hana St. Juliana, 14; Madisyn Baldwin, 17; Tate Myre, 16; and Justin Shilling, 17. Seven other people, including a teacher, were seriously wounded.

A motive in Tuesday’s shooting remains unclear, though authorities have said they found a video on Ethan Crumbley’s phone that he appeared to have made the night before the shooting in which he discussed killing students.

In a video message published Thursday, Tim Throne, leader of Oxford Community Schools, addressed the suspect being called to the office prior to the shooting but said “no discipline was warranted.”