A 15-year-old boy accused of plotting to attack his high school on the anniversary of the Columbine massacre pleaded guilty to a lesser charge of attempted conspiracy.

The teenager, who has not been identified since his arrest last month along with 17-year-old Michael McDonough, entered the plea Tuesday in Family Court on Long Island. He originally was charged with fifth-degree conspiracy, a misdemeanor.

Investigators began looking into the pair after finding a journal describing a plot to attack Connetquot High School in Bohemia with guns and explosives.

Police said they found notes referring to the April, 20, 1999, attack at Colorado's Columbine High School, where two student gunmen killed 12 classmates and a teacher before killing themselves. They determined that the two Long Island teens had looked for ways to purchase weapons but never acquired any.

McDonough was charged as an adult with misdemeanor conspiracy, punishable by up to a year in jail, and is free on $50,000 bond. His court-appointed lawyer, Robert Flick, has said his client was "barely" culpable in the alleged plot.

The 15-year-old was sent to a children's psychiatric center while awaiting sentencing and is due back in court Aug. 21.