First, a teacher found Ethan Crumbley searching online for ammunition. The next day, there was an alarming note on his desk: “The thoughts won’t stop. Help me.”
School officials met with Mr. Crumbley, 15, and his parents, informing them that he needed to begin counseling within 48 hours. After his parents resisted bringing him home, administrators allowed him to stay in school.
Shortly afterward, Mr. Crumbley fatally shot four students, according to the prosecutor in Oakland County, Mich., who laid out that stunning series of events on Friday while announcing involuntary manslaughter charges against the parents.
Now, Oxford High School’s actions are also under a microscope, prompting questions about the school’s responsibility, and whether there could be legal repercussions for administrators. Asked if her office was looking into the conduct of school officials, Karen M. McDonald, the prosecutor, said, “The investigation is ongoing.”
Catherine J. Ross, a law professor at George Washington University and expert on student rights, said she found the school’s reaction “truly astounding.”
It was well within the school’s rights to require Mr. Crumbley, who has since pleaded not guilty to murder and terrorism charges, to leave campus, Professor Ross said.
If the parents refused to take Mr. Crumbley home, it was the legal and ethical responsibility of the school, Professor Ross said, to “remove the student from the classroom and put them in a safe place — safe for other people and safe for themselves.”
School officials have defended their actions. In a videotaped statement posted online on Thursday, the superintendent of Oxford Community Schools, Tim Throne, said that Mr. Crumbley had no disciplinary history. “No discipline was warranted,” Mr. Throne said. “There are no discipline records at the high school.”
But Ms. McDonald suggested there were unanswered questions.
When asked whether the school staff should have reported Mr. Crumbley right away to law enforcement, she said: “Any individual who had the opportunity to stop this tragedy should have done so. The question is what did they know and when did they know it.”
A spokeswoman for the district did not respond to requests for comment on Friday.
Chris Dorn, a school safety consultant with the nonprofit Safe Havens International, said it was advisable for schools to call law enforcement if there was suspicion that a student might be armed.
Mr. Dorn has conducted investigations into lapses that led to past school shootings, finding that administrators sometimes worry that calling the police will violate a student’s rights. Other times, they have simply failed to take a threat seriously enough.
“Part of it is that people are just generally nonconfrontational,” Mr. Dorn said. “School staff are often slow to recognize danger because it’s not part of their everyday.”
While Oxford High School conducted active shooter drills several times per year, “There is a lot of focus on responding to the active shooter, but not necessarily on the prevention for them,” he added.
It is historically very challenging to hold a school district legally responsible for a shooting, said Chuck Vergon, a professor of education law at Youngstown State University.
A majority of past school shooting cases featured some kind of warning in advance of potential violence, he said. But it is difficult in most state courts to meet the required standard of proving gross negligence on the part of school officials — that they acted in “wanton and willful disregard” for the safety or well-being of others, he said. “That standard has usually shielded school officials in most school shooting cases from civil liability.”
But the Oxford school system will most likely face years of litigation over the shooting, if recent history is any guide.
“I definitely think that there’s going to be a lawsuit,” said Mike Kelly, a lawyer in Northville, Mich., who specializes in representing students who face school expulsion — including one student who recently faced expulsion by another Michigan district for having a hunting rifle in the car he parked on school grounds.
“There is some culpability and responsibility here on the part of the school,” Mr. Kelly said.
In one notable case, when a substitute teacher was told of a threat but failed to take action, the insurance company for Marysville School District in Washington paid $18 million to the families of four dead students, as well as to one student who was injured.
While school district settlements are not rare, victims’ families face obstacles.
In 2018, a judge in Connecticut threw out claims filed by the parents of two victims of the 2012 Sandy Hook massacre, in which 20 first graders and six adults were killed. The judge concluded the school district was immune from such lawsuits.
This year, schools in Broward County, Fla., reached a $25 million settlement with both survivors and families of the victims of the shooting at Marjory Stoneman Douglas High School in 2018, which left 17 people dead and another 17 wounded. The settlement followed a court decision capping the school system’s liability at $300,000 had the victims won at trial.
In the Michigan shooting, a potential lawsuit would probably turn on the question of whether the school took strong enough action to protect students after a teacher happened to see Mr. Crumbley’s disturbing drawing, which included a gun, a person who had been shot and a plea for help.
The fact that Mr. Crumbley was said to have no disciplinary record creates what Mr. Kelly called “a gray area” and could become pivotal in any lawsuit claiming the school was culpable because it failed to remove him from campus.
Shannon Watts, founder of Moms Demand Action for Gun Sense in America, said school officials should have searched Mr. Crumbley’s bag for weapons.
But she said that the steps to prevent gun violence begin far before someone brings a weapon onto school grounds. Ultimately it is lawmakers, not school officials, she argued, who have the power to prevent shootings by passing secure gun storage laws or red flag laws, which allow the police to temporarily confiscate firearms from people who are deemed by a judge to be a danger to themselves or others.
“You’re putting educators in an impossible position because they don’t really have the tools to proactively prevent guns from coming into the school,” Ms. Watts said.