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Teen Charged As Adult, Told Police She'd Carry Out School Attack If Let Go

By Tom Mustin

CASTLE ROCK, Colo. (CBS4) - One of two teenage students at Mountain Vista High School will be charged as an adult after an alleged planned attack against the school.

Family members of Sienna Johnson, 16, silently filed out of the Douglas County courtroom after the ruling Tuesday afternoon. District Attorney George Brauchler says the ruling is the correct one.

Sienna Johnson
Sienna Johnson (credit Instagram)

"We do this pretty rarely, and when we do it's because of the information we have and the concern that info created for us," Brauchler said.

Johnson had allegedly planned what the sheriff's office called a "credible attack" with a fellow female student. In court Tuesday prosecutors called Johnson "dangerous." They say she had drawn a map showing where people in the school would be standing on the day of the planned attack. Next to the map were the letters N-B-K, or "Natural Born Killers," referring to the film.

Johnson also posted disturbing images on her Tumbler page, and allegedly had begun experimenting by hurting her pets. She also had purchased a BB gun to practice her aim.

Sienna Johnson
Sienna Johnson (credit Instagram)

The district attorney's office says after being arrested Johnson told them she would still carry out her plan if let go.

"The details haven't come out yet, but suffice it to say there is enough out there that I think people can conclude that this has the potential to be something that is of extreme significance to members of this community," Brauchler told CBS4's Tom Mustin.

The plot was discovered through a Text-A-Tip to Douglas County authorities on Dec. 12. The attack had been planned for the following week. Mountain Vista parents and students were stunned.

"I don't know what's going on with our kids, but we've got to figure this out," said Mountain Vista parent Lisa Labofsky.

Sienna Johnson
Sienna Johnson (credit: Mountain Vista High School yearbook photo)

Sophomore Cooper Johnson agreed.

"To know that someone is interested in that stuff is disturbing and weird," Cooper Johnson said.

Sienna Johnson is facing charges of conspiracy to commit murder. She's being held on a $1 million bond. Brauchler says despite the teen's age justice needs to be served.

"This is important to get right, this is not a case that we want to guess wrong on, either for the juvenile, or for the community," Brauchler said.

A new hearing has been set for March 30. Johnson's attorneys will try and convince the judge to move the case back to juvenile court.

The other 16-year-old suspect will undergo a psychiatric examination before a decision is made on whether she'll be tried as an adult. She is due in court Jan. 14.

Tom Mustin is CBS4's Weekend Anchor. He has been with CBS4 since 2002, and is always looking for great story ideas. Follow Tom on Twitter @TomCBS4.

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