Teenage girls 'planned Columbine massacre copycat attack' at high school ten miles away

The two 16-year-old have been charged in an adult court

Prosecutors say the girl planned to attack their classmates at Mountain Vista High School

Investigators in the western state of Colorado believe two 16-year-old girls - at least one of them obsessed with the 1999 Columbine massacre - planned a copycat attack at their own school located just ten miles away.

Prosecutors this week charged the second of the two teenagers, formally accusing her of plotting the assault on classmates and staff at Mountain Vista High School, located in a suburb of Denver.

Brooke Higgins appeared in Douglas County District Court on Thursday, where she was charged with conspiracy to commit first degree murder. Her friend and alleged co-plotter, Sienna Johnson, was handed similar charges last week when she appeared in an adult court. Bail for both of them was set at $1m.

Prosecutors say they have seized a journal kept by Sienna Johnson in which she had written poetry and macabre drawings (Twitter)

Reuters reported that both girls attended the school in the Denver suburb of Highlands Ranch and were arrested in December after two anonymous tips to authorities.

Prosecutor Mark Hurlbert said told the judge that Higgins was fascinated with the 1999 Columbine High School massacre, where two students shot dead a teacher and 12 students before killing themselves.

He said that the teenager wrote in a journal that she wished she could have taken part in that massacre and took a photograph of herself outside Columbine High.

She 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 about to take place, he said.

Brooke Higgins appeared in an adult court this week (Family handout)

Last week, prosecutors said a journal was seized from Sienna Johnson in which she had allegedly drawn a map of the school and recorded the movements of security officers.

She had also allegedly taken steps to acquire firearms and had gone target shooting with a pellet gun. She had also written poetry and macabre drawings.

“I feel very stranded and alone,” she wrote in one entry. On the same page she reportedly highlighted the words “They’re still after you.”

Dagny Van Der Jagt a lawyer for Brooke Higgins, issued a statement distancing her from the other school girl.

She said: “The girls were casual school acquaintances who had associated with each other for a brief time.”

She added: “They have different backgrounds, personalities, motivations and behaviours.”