Naomi Lewis, whose 12-year-old son threatened to shoot people with a high-powered rifle at his Prince William County middle school in June, pleaded guilty yesterday to a felony weapons charge for leaving the gun and ammunition locked in her van at the school.

Lewis, 39, of Haymarket, was found guilty of possession of a weapon on school property in Prince William County Circuit Court. Assistant Commonwealth's Attorney Claiborne T. Richardson II recommended that Lewis serve a five-year suspended sentence on probation and undergo mental health and family counseling.

Judge Richard B. Potter will sentence Lewis on Jan. 6. He told her that he could choose from a range of punishments: a $2,500 fine and up to a year in jail; or one to five years in prison.

A Prince William detective testified yesterday that on June 18, Lewis, who was a cafeteria worker at Bull Run Middle School, realized when she arrived with her son that he had put weapons and ammunition in the back of the van. They were inside a nylon bag -- the kind used to hold folding camp chairs -- with the guns' barrels protruding.

Then "she covered them over" with a towel and locked the van, and both entered the school, Detective Stephen Piaskowski testified. He said Lewis initially denied knowing about the weapons when he interviewed her hours after the incident. She later apologized when police confronted her with her son's story.

A person can be exempt from the state law barring weapons on school property if the weapons are inside a "closed container," which includes but is not limited to vehicle trunks. Even though Lewis was driving a car that did not have a trunk, putting a towel over the weapons "does not make the bag a closed container," Richardson said in an interview.

Lewis did not testify and declined to comment through her attorney.

The boy, then a seventh-grader, sneaked out to the van, opened it with a key his mother did not know he had, and brought the weapons and ammunition inside the school. He went into a bathroom next to the administrative office, changed into camouflage gear and began loading a .30-06 rifle. An assistant principal on a routine check heard the boy loading the weapon and rushed to the office to call for help.

Lewis's son then burst into the office, ordered about a dozen people to "get down" and pointed his rifle at a woman calling for help. A teacher eventually talked him out of the siege, and police arrested him. No shots were fired, and no one was hurt or killed.

The boy's father has said that his son was "tormented" by bullies. Friends and neighbors have said he was picked on for his weight and clothes.

The boy, now 13, was convicted of felony weapons and abduction charges in August. He was sentenced last week to a state juvenile facility for an indefinite amount of time, to a maximum age of 21. At a Nov. 24 court hearing, a judge could release him or send him to a juvenile home.

If the youth is sent back to the state facility, Department of Juvenile Justice officials will determine when he is released.

Naomi Lewis, the boy's mother, in court with her attorney, Steven Smith. The prosecutor recommended that she be given a suspended sentence.An evidence photo shows a gun that was brought into Bull Run Middle School in June by a seventh-grader who threatened people in the building.