A troubled teenager accused of plotting a school attack built up a stash of weapons with the help of his mother, authorities said.

Michele Cossey, 46, was arrested Friday on charges of illegally buying her home-schooled son, Dillon, a .22-caliber handgun, a .22-caliber rifle and a 9 mm semiautomatic rifle with a laser scope.

The parents were indulging the boy's interests because he was unhappy, not knowingly aiding a school assault, Montgomery County District Attorney Bruce Castor said Friday. The parents didn't know of the teen's plans, but "by virtue of her indulgence, she enabled him to get in this position," Castor said.

Authorities have said they do not believe an attack was imminent and are not even certain one would have occurred.

"This was a smart kid that clearly believes he was picked on and was a victim," Castor said. "He had psychological issues and began to act out on those feelings."

Dillon Cossey, who was arrested Wednesday, felt bullied and tried to recruit another boy for a possible attack at Plymouth Whitemarsh High School, authorities said. The teen previously attended middle school in the district, but had been taught at home for more than a year after voluntarily leaving school.

Acting on a tip from high school student, Lewis Bennett III and his father, police searched the boy's bedroom and found the 9 mm rifle, about 30 air-powered guns modeled to look like higher-powered weapons, swords, knives, a bomb-making book, videos of the 1999 Columbine attack in Colorado and violence-filled notebooks, Castor said.

The mother bought the semiautomatic rifle at a gun show on Sept. 23 and provided police with a receipt, investigators said in court papers. The teenager said the two .22-caliber weapons were stored at a friend's house.

She was charged with unlawful transfer of a firearm, possession of a firearm by a minor, corruption of a minor, endangering the welfare of a child and two counts of reckless endangerment, and later released on bail. She did not comment at the hearing.

Her attorney, Tim Woodward, said, "I'm sure she loves her kid."

The teen, who also had a brief court appearance Friday, was ordered held at a juvenile facility while he receives psychiatric evaluation. He was charged with solicitation to commit terror and other counts, but his lawyer, J. David Farrell, stressed that all but one of the weapons prosecutors put on display were pellet guns and air rifles.

At a press conference in their Conshohocken, Pa. home, the parents of the teen who tipped police off about the possible school attack, praised their son.

"We are really proud of our son, his maturity, and the way he is handling the media," said Lewis Bennett, Jr., the boy's father. "Wednesday my son learned of new information and that added to the information he had. That is what seemed to make it a more serious event. That is why we went to the police department."

While Dillon Cossey had been to their house, the teen's mother was concerned about him.

"(His) preoccupation with guns, when he would call the house and my son wasn't available, he would call persistently," said Lewis Bennett III's mother. "Things that make a red flag, but not sure of what is going on. He was always polite. A soft spoken child child."

It is legal for children to possess air guns in Pennsylvania. Farrell also noted it is legal for a minor to fire weapons under adult supervision and said he didn't believe the students at Plymouth Whitemarsh were in any danger.

"They're showing 30 guns on a desk that appear to be handguns and saying this was a Columbine in the making," Farrell said. "That's simply not borne out by the facts."

Dillon Cossey told investigators he was planning an attack on the school, Castor said, but authorities do not believe he was close to pulling it off. Castor said he believes the teen Cossey asked to help him was the first person he approached for assistance.

On his MySpace page, Dillon Cossey made frequent references to Eric Harris and Dylan Klebold and describes their 1999 massacre at Columbine High School as one of his interests. The page, headlined "Mess with the best, Die like the rest," features tribute videos to the Columbine shooters and includes a still from surveillance video of the attack.

Police, who searched the boy's home with his parents' permission, also discovered seven explosive devices Castor has described as homemade grenades: plastic containers filled with BBs to which gunpowder could be added. Authorities said one was operable and the others had been in the process of being assembled.

The search did not turn up any ammunition for the semiautomatic rifle.

Castor said he suspects Cossey "was a target for bullies because he was overweight and not fully developed socially," but that mental problems might have exaggerated the effect of the bullying.

"I have read things that he wrote. ... He has severe mental disturbances," Castor said.

Authorities said Friday that the boy's father also tried to buy his son a rifle in December 2005, but was not allowed to because he was a felon.

Frank Cossey was sentenced to house arrest for lying about his criminal record when he went to buy a .22-caliber rifle, police said Friday. On his application he said he had never been convicted of a felony, but he had pleaded guilty in 1981 to manslaughter in a drunken driving death in Oklahoma and sent to prison, police said.

The boy's arrest came the same day a 14-year-old in Ohio opened fire at his Cleveland high school, wounding four before killing himself.

The high school student who tipped off police with his father told the Philadelphia Daily News he was "sick of hearing about all these school shootings."

"I didn't want another kid to do the same thing and keep this chain of events going on," Lewis Bennett said.

Michele Cossey faces a maximum sentence of up to seven years in prison on the gun-transfer charge alone, but the prosecutor expects she would get a lighter sentence.