Lew Bennett III acknowledged his role in the break-ins at a hearing at the Montgomery County youth center. The proceeding were not closed because Bennett and two other juveniles involved are 14 or older and are charged with a felony.

The three, all Plymouth Whitemarsh High School ninth graders, acknowledged that they broke into the home of Dillon Cossey in recent weeks.

Cossey is the student who was arrested in October and admitted planning an attack on the high school.

Bennett was later praised by President Bush for tipping authorities to Cossey's plan.

The Inquirer is identifying Bennett because of his previous role in the Cossey case, and his meeting with Bush.

The president was in the area for a political fund-raiser on Oct. 30 when he greeted Bennett on the tarmac of Philadelphia International Airport three weeks after Bennett tipped off police.

"The president wanted to thank him for doing the right thing," White House spokesman Alex Conant said at the time.

Cossey and Bennett had lived near each other in Plymouth Township.

The three youths entered Cossey's home through a bedroom window. The three surrendered to authorities yesterday and spent last night in custody. They will remain in custody until a disposition hearing within the next 20 days.

A police search of Cossey's bedroom after Bennett's tip produced an arsenal of weapons, including a variety of knives, a number of air-powered BB guns, a poem Cossey wrote about a school shooting, and violent video games and publications. Cossey had no ammunition for the weapons, and some officials have said that no attack was imminent.

The teen, who was home-schooled at the time, said his mother, Michele M. Cossey, bought him three guns.

That resulted in weapons charges against her, which are pending.

A judge has said the parents' lack of discipline and the mother's obsession with her son - culminating in her decision to buy him guns - led to his emotional problems.

Some authorities believed that Dillon Cossey was reacting to having been bullied. His home and computer revealed an obsession with Dylan Klebold and Eric Harris, the students responsible for the 1999 Colorado school massacre, who are regarded by some teens as bully vigilantes. Cossey downplayed that theory, but his lawyer suggested that his client's behavior was typical of such victims.