By Keith Coffman
DENVER (Reuters) - Colorado prosecutors on Thursday charged the second of two 16-year-old girls as an adult with conspiracy to commit first-degree murder in connection with plans to attack their high school, authorities said.
Brooke Higgins appeared in Douglas County District Court where she was formally accused of plotting to kill classmates and staff last month at Mountain Vista High School, said Assistant District Attorney Mark Hurlbert.
Her alleged accomplice, Sienna Johnson, also 16, was charged last week in adult court with identical charges. Prosecutors held off filing charges against Higgins last week pending the completion of a psychiatric examination.
Both girls attended the school in the Denver suburb of Highlands Ranch, and they were arrested in December after two anonymous tipsters alerted authorities to the plot, police said.
Douglas County District Court Judge Paul King has set $1 million bonds for both teens.
Prosecutors said the seriousness of the alleged crimes warranted trying the cases in adult court, but lawyers for both girls are seeking to have their cases sent back to juvenile court.
At Thursday's hearing, Hurlbert said prosecutors told King that Higgins was fascinated with the Columbine High School massacre, where two students in a neighboring county shot dead a teacher and 12 students before killing themselves in 1999.
Higgins wrote in a journal that she wished she could have taken part in that massacre and even snapped a photograph of herself outside Columbine High, Hurlbert said.
Higgins also searched online for how a juvenile could buy firearms and told a friend she would warn her to stay away from the school when the attack was imminent, he added.
Prosecutors said last week that investigators had seized a journal from Johnson in which she allegedly drew a map of the school and recorded the movements of security officers. She also took steps to acquire firearms, prosecutors said, and had gone target shooting with a pellet gun.
Higgins' lawyer, Dagny Van Der Jagt, issued a statement distancing her client from Johnson.
"The girls were casual school acquaintances who had associated with each other for a brief time," the lawyer said. "They have different backgrounds, personalities, motivations and behaviors."
Van Der Jagt said Higgins' parents have cooperated with authorities by allowing their home to be searched for weapons -none were found - and by voluntarily submitting their daughter to the mental-health evaluation.
Neither girl has entered a plea in response to the charges.
(Reporting by Keith Coffman; Editing by Daniel Wallis and Cynthia Osterman)