Douglas District Court Judge Paul King on Friday sentenced Sienna Johnson, 17, of Highlands Ranch, to five years in the Department of Youth Corrections after she pleaded guilty in a plot against Mountain Vista High School.
On June 7, 2017, Johnson pleaded guilty in juvenile court to conspiracy to commit first-degree murder, a Class 2 felony, for a plan to shoot students at the school. She pleaded guilty in adult court to felony menacing with a real or simulated weapon, a Class 5 felony.
“This agreement strikes the balance of making sure the community is safe but not throwing away the key on Sienna,” said Senior Chief Deputy Jason Siers, who prosecuted the case. “We want her to be successful. But it was a horribly serious case, and we have to have accountability.”
The judge agreed.
“When something like this surfaces, it has to be treated seriously, as it was in this case,” Judge King said. “Plenty of people have tough home lives, and they don’t have thoughts of mass murder.”
Johnson was arrested in December 2015 for her role in a murder plot at her high school in Highlands Ranch and has been in custody ever since.
Her five-year sentence on the conspiracy charge does not include credit for time served.
It will be followed by four years of supervised probation on the menacing charge. If she is not successful during probation, she faces a maximum of six years in the Department of Corrections.
The adult felony conviction will remain on her criminal record.
“This disposition gives this defendant a legitimate chance at a future of being a responsible, law-abiding member of society, while ensuring the community is not put at risk,” said District Attorney George H. Brauchler. “This was no joke or fantasy. This was outrageous behavior demanding of a high level of accountability. The supervision involved gives the juvenile defendant the greatest chance of rehabilitation.”