An 18-year-old man suspected of plotting a killing spree at a high school was sentenced to five years in state prison.

Johnny Alvarez Casas pleaded no contest last month to conspiracy to commit a crime and possession of bomb-making ingredients. He was sentenced Thursday.

Casas was a former student at Quartz Hill High School in the Antelope Valley, 60 miles north of Los Angeles.

Sheriff's officials said Casas and another ex-student, now 17, confessed that they planned to attack the school on Valentine's Day, planting homemade bombs and shooting students who had made fun of them.

Casas' attorney has said the teens were intimidated into making false confessions by authorities who overreacted.

Casas and the other student were arrested a year ago after a 16-year-old girl told an assistant principal she heard they were planning to cut off her arms and legs.

Casas, who was 17 at the time, was prosecuted as an adult. The other teen will be tried as a juvenile on charges of conspiracy to commit murder and making a criminal threat. If convicted, he could be sentenced to Juvenile Hall until he turns 25.