Evidence released in deadly school plot

CASTLE ROCK, Colo. -- Now that Sienna Johnson and Brooke Higgins have been sentenced for their plot to commit a massacre at Mountain Vista High School in Highlands Ranch, Douglas County prosecutors have released evidence found in the girls' journals, social media accounts and a recorded interview Johnson gave to a sheriff deputy.

Johnson was on a mental health hold in December 2015, when a detective interviewed the now-17-year-old about her plan to kill students and staff at the high school she attended.

"Back in September I started getting like a really strong hate for my family and everyone around me because I felt like I wasn't taken seriously and I wasn't here and I was a joke to everyone. I wanted to be heard," Johnson said to the detective.

She admitted buying a BB gun just a week earlier for target practice and talked of making explosives.

"I was trying to make aerosol bombs," she said.

Johnson's journal shows a list of guns and their prices found at Armlist.com.

The diary shows drawings of weapons and a person being shot with the caption, "I wish I was dead."

The journal begins with a list of favorite movies, including "Texas Chainsaw Massacre," "Halloween" and "Natural Born Killers" followed by the admission, "I glorify serial killers."

She went on to write, "Before I blow up the school, I need to find a way to kill my family first."

Johnson told a detective her plot moved from fantasy to reality when she befriended Higgins in December 2015.

"She asked me, she was like let's shoot up the school I'm not joking. ... That's when it came real to me. Before, it was a fantasy, but when I met someone who also wanted to do it, it became real," Johnson said.

In Johnson's journal, she writes, "I wish I'd done Columbine with Eric and Dylan. They were so incredibly smart. They saw the strings that control the system and they weren't f---ing sheep."

Through the social media app Snapchat, Higgins would tell Johnson, "Have to get guns get good at shooting them plan out how well get the most ppl then do it. Let's become best friends. Colombine (sp) part 2."

The girls had a map of the high school with hand-drawn notes marking the library as "most crowded during lunch and 3rd period."

When a detective asked Johnson what a mass killing would accomplish, she responded, "It would be taking people down with me. People would know what I felt. People would know how much pain I was in. People would know how much I hated everyone. I would be making a name for myself."

It's the girls' pain that is perhaps most haunting in their journals.

"I'm tired of being the only one suffering," Higgins wrote. "I'm going to make everyone else suffer."

Johnson confides the most important warning of all.

"If your child tells you they have a problem, help them or get them help," she wrote.

Both girls have been ordered to undergo mental health treatment while they're in juvenile detention.

If Higgins completes her sentence, she can get her criminal record wiped clean. But if she violates probation after serving a three-year sentence, she could serve an additional eight to 24 years in adult prison.

Johnson's sentence calls for five years behind bars followed by four years of probation.

If she violates probation, she could serve an additional two to six years in prison. She will always carry a felony conviction on her record.