NORRISTOWN, Pa. — Tired of being bullied, an awkward, overweight middle-schooler left his peers behind last year in favor of home-schooling.

But if the bullying ceased, Dillon Cossey found no relief from his demons.

Cossey amassed dozens of BB guns, swords, knives and homemade explosives in his parents’ suburban Philadelphia home while quietly planning an attack at the local high school, authorities said.

Perhaps more troubling, they say, his mother provided more firepower in the form of three deadly weapons that she bought for her only child — a small-caliber handgun, a small-caliber rifle and a 9 mm semiautomatic rifle with a laser scope.

“They (the parents) feel sorry for him. They were overindulgent,” Montgomery County District Attorney Bruce L. Castor Jr. said Friday, when both Cossey and his mother Michele appeared in court on related charges.

“I don’t think that they had any idea that he was dangerous,” Castor said. “She’s not any hardened criminal.”

Michele Cossey, 46, grimaced and wept Friday as a judge read the charges against her.

Her son was arrested Wednesday after an acquaintance shared Dillon Cossey’s plan to attack Plymouth Whitemarsh High School with his own parents and then with police.

Police searched Cossey’s bedroom and found the 9 mm rifle and about 30 air-powered guns modeled to look like higher-powered weapons, along with a bomb-making book, videos of the 1999 Columbine attack in Colorado and violence-filled notebooks, Castor said.

Montgomery County District Judge Paul Tressler on Friday ordered the teen held at a youth facility at least until he undergoes psychiatric testing. He also asked for academic progress reports on the teen, who was described by Castor as a “smart kid” with “mental disturbances.”

“I suspect that he was a target for bullies because he was overweight and not fully developed socially,” Castor said. “I also think that his mental illness would have exaggerated the effect of the bullying.”

Dillon Cossey is charged with solicitation to commit terror and other counts.

Michele Cossey, who runs a deli near the county courthouse, declined to comment in court Friday, as did her husband Frank.

A neighbor spoke well of them.

“That family would not hurt anybody, the son included,” said Kathy Joslin, a lifelong friend. “She never would have bought him something thinking that this was something more than just buying him a toy. She made a mistake. She’s human.”

Dillon Cossey told investigators that he was planning an attack at Plymouth Whitemarsh, which some of his former schoolmates now attend, according to Castor.

However, no such attack was imminent, the prosecutor said. The tipster, 14-year-old Lew Bennett III, apparently interrupted the plan in the early stages, authorities said.

“I just don’t believe that students at Whitemarsh were in any real harm,” said defense lawyer J. David Farrell, who represents Dillon. He noted that police found only one firearm in the family home and no ammunition.

“I understand that in this climate, people were concerned,” Farrell said. “He (Dillon Cossey) also understands the gravity of the situation.”

The two small-caliber weapons were being stored at a friend’s home, police said. Michele Cossey had also bought them for her son, one of them in May 2005, the same month the boy turned 12, according to the police affidavit filed in her case.

Her husband had tried to buy their son a gun that year, but came under scrutiny because of a prior manslaughter conviction stemming from a 1981 drunk-driving case in Oklahoma, court records show. Frank Cossey, 56, had spent about six years in prison on the manslaughter charge.

He is on house arrest for failing to disclose his criminal record when he applied to buy the .22-caliber rifle at a sporting goods store.

Michele Cossey bought the semiautomatic rifle at a gun show last month, police said.

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.

Her attorney, Tim Woodward, said, “I’m sure she loves her kid.”

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.

“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.”

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.

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