VILLISCA, Iowa?A teen-ager has been charged with administering a dangerous substance after he allegedly plotted to poison the punch at the Villisca High School prom.

Robert David Dumler, 15, initially faced a more serious felony charge of terrorism. But Montgomery County Attorney Bruce said Monday that the terrorism charge must involve firing a weapon or the use of an incendiary device.

Dumler was arrested Friday night after reports that he planned to spike the punch at Saturday’s dance with a substance that would make people seriously ill or kill them, Police Chief Butch Rulla said. Dumler allegedly wanted to “get even” with several students.

Rulla said another teen turned over a plastic vial of an unknown liquid that belonged to Dumler. The liquid was being tested.

Dumler was being held in the Southwest Iowa Juvenile Detention Center pending a court appearance June 18.