A judge dismissed charges on Thursday against a former assistant principal in Virginia who was accused of failing to act before a 6-year-old child who had brought a gun to school shot a teacher.

The case against the former school official, Ebony Parker, began on Jan. 6, 2023, when the boy in first grade shot his teacher, Abigail Zwerner, at Richneck Elementary School in Newport News. Ms. Zwerner survived but sustained serious injuries after the bullet pierced her left hand, punctured her lung and narrowly missed her heart.

Witnesses in the trial testified that Ms. Parker had received warnings that the student had brought a gun, and prosecutors said she had a duty to intervene and did not. Ms. Parker was charged with eight felony counts of child abuse and neglect. She has since resigned from her position at Richneck.

Prosecutors had argued that Ms. Parker alone had the authority under school policy to intervene by ordering a full search of the boy. By failing to do so, they argued, she was criminally liable for the violence that followed.

Curtis Rogers, Ms. Parker’s attorney, argued that she did not bear primary responsibility for preventing the shooting. That duty, he argued, lay with the teacher, Ms. Zwerner, and those directly in contact with the student during the school day.

Had those people genuinely believed the student posed an immediate threat, they could have taken action to prevent it, such as separating the student from the rest of his class, he contended. “Based upon their actions, there was no crisis, there was no gun,” Mr. Rogers said.

On the third day of the trial, the judge said that Ms. Parker’s actions did not constitute a crime under existing state law.

“There is no precedent for what is before the court,” Rebecca M. Robinson, the Newport News Circuit Court judge, said.

As she dismissed the case with prejudice — meaning it cannot be tried again — Judge Robinson added that the case was “too novel” for a judge and jury and suggested the issue was better suited for Virginia’s legislature.

After the ruling, Ms. Parker put her head on the desk in front of her and cried. She declined to speak to news outlets immediately after the proceeding.

The decision adds to a mixed record of prosecutors attempting to hold adults responsible for failing to anticipate and prevent school shootings. The mother of the student who shot Ms. Zwerner was sentenced in December 2023 to two years in prison after pleading guilty to felony child neglect. (The child was not criminally charged.)

In another school shooting by a juvenile in Georgia, a father was found guilty of murder. And parents of a young school shooter in Michigan were convicted of involuntary manslaughter. After shootings in Parkland, Fla., and Uvalde, Texas, law enforcement officers were acquitted.

In November, a jury awarded Ms. Zwerner, who no longer works at the school, a $10 million judgment in a civil suit against Ms. Parker, arguing that she had been negligent by ignoring several reports from staff members that the boy might have brought a gun to school that day.

A lawsuit on behalf of students at the elementary school against the school district, which also names Ms. Parker as a defendant, is still pending, according to statements made by Ms. Parker’s defense team during the trial.

Ms. Zwerner was among those who testified in Ms. Parker’s trial this week, recounting on the stand how she had observed the student, who had a history of violent and troubling behavior, acting strangely in the hours leading up to the shooting.

Parents of other students who were in the classroom when the shooting took place also testified, along with other Richneck staff members who said they had tried to alert Ms. Parker to the danger.

One of them, Amy Kovac, a reading specialist at the school, said she had heard from the student’s classmates that he had a gun in his backpack. She told the court that she had relayed that information to Ms. Parker, who declined to authorize a search, on the grounds that the student’s mother was coming to pick him up.

Later, Ms. Kovac said she was the first to arrive in the classroom after the student had shot Ms. Zwerner. His classmates had fled, and she found the boy alone with the handgun abandoned on the floor.

Ms. Kovac said she grabbed the boy, who did not resist, and held him between her arms and legs for what “felt like eternity” until the police arrived.

Prosecutors said shortly after the shooting that they would not file criminal charges against the boy, who told investigators he had climbed a dresser to take his mother’s loaded 9-millimeter handgun from her purse.

The Hampton Commonwealth’s Attorney’s Office did not immediately respond to a request for comment after the decision.

Billy Witz contributed reporting.