A Pennsylvania woman has admitted she helped her troubled 14-year-old son build a cache of weapons to help him fend off bullies.

Prosecutors say the boy was planning a deadly attack at a suburban Philadelphia high school.

Forty-six-year-old Michele Cossey pleaded guilty Tuesday in Norristown to one count of child endangerment.

Her son planned an assault last year on Plymouth Whitemarsh High School. The boy had been bullied over his weight, had left public school and was being home-schooled.

A prosecutor says he thinks Cossey was trying to boost her son's self-esteem and described her motives as misplaced. A judge did not immediately set a sentencing date.

The teenager is in a juvenile treatment facility.