15-year-old sentenced for ‘calculated, predatory’ Tri-City school shooting plot

The student who developed a detailed plan for a mass shooting at Kamiakin High in Kennewick last year received the maximum sentence allowed in juvenile court Monday.

Following an emotional hearing, Superior Court Judge Jacqueline Shea-Brown ordered Mason Bently-Ray Ashby, now 15, to be jailed for about five more years, until he turns 21.

Because Ashby committed the crime of attempted first-degree murder when he was just 14, Washington state law does not allow him to be tried as an adult.

He also was found guilty by Shea-Brown of one count of threats to injure property and 11 counts of unlawful possession of a gun.

The Benton County sentence that will keep him locked up until he turns 21, rather than releasing him sooner, was only possible before Shea-Brown ruled that a sentence longer than the standard range was justified because of the potential danger Ashby posed to the community.

She said he was at high risk to reoffend and that the “horror” of his actions would not be forgotten by those impacted.

Ashby was armed with one of his grandfather’s guns after figuring out the code to his gun safe and created maps detailing his planned mass shooting last September.

He targeted rooms at Kamiakin High, videotaped a “dress rehearsal” walk-through at the school and wrote a manifesto found after the planned shooting.

He was arrested a day after he videotaped the dress rehearsal.

Ashby was dressed Monday in a suit and tie and listened impassively as school leaders and employees talked in the Kennewick courtroom. But later he became emotional as he spoke to the judge, laying his head on the table where he was sitting and crying.

Kamiakin staff discuss pain, anxiety

The planned shooting was averted, but the trauma to the Kamiakin students and their parents, the school staff and leadership and the community continues, Shea-Brown heard from school leaders and others.

“This incident created a deep sense of violation,” Kamiakin Principal Chris Chelin told the judge.

Students and parents were so fearful that many students stayed home from school in the weeks just after Ashby’s “well-constructed, color-coded plan laid out to inflict maximum harm” was revealed, said Heather Atterberry, a teacher for more than 20 years.

One of the school’s most dedicated teachers working in one of the buildings targeted decided to leave education, and Atterberry and others are looking for ways to leave the teaching profession because they don’t feel safe, she said.

It was the most exhausting year she has ever had, and that included the COVID years, she said.

Another teacher, in an anonymous letter read to the court, said that their classroom was one targeted on Ashby’s color-coded map. They were terrified that their son had several classes with Ashby and could have been coming to his parent’s classroom to have lunch at the time of the shooting, they said.

When the teacher was invited by a family to watch a Kamiakin volleyball game, they started shaking and crying in the stands and had to leave because they felt so unsafe, the letter said.

“If it was up to me, I would try you as an adult, and you would receive a significant sentence as you are a psychopath and too dangerous to be around the general public,” the letter said.

Another teacher who provided a statement anonymously said they would likely be dead if the shooting had not been averted. It was a 12-year-old in Florida who saw a TikTok video Ashby had posted and the boy’s brother reported it to the Federal Bureau of Investigation. Within 24 hours, Ashby was arrested.

The teacher spent time looking at bullet-proof vests and has been jumpy and irritable, startling whenever a car backfires, they said.

Teachers described their students as angry and anxious, and the energy that pervaded the school made it hard for them to learn, to trust and to be a kid.

Ashby’s actions were not a prank or a mistake, said Gabe Galbraith, the Kennewick School Board president, but a deliberate act that terrorized people and struck and the foundation of public trust.

Ashby should be punished accordingly, he said.

What made Ashby’s crime particularly chilling was “its calculated, predatory specificity,” said Lance Hansen, Kennewick School District superintendent.

The psychological trauma the crime “robbed Kennewick families of their peace of mind,” he said.

He asked the judge for a sentence that would send an unmistakable message to those who plot to harm children that they will face the strictest consequences.

‘Hurts so bad,’ Ashby says

Ashby’s grandmother, Wendy Ashby, also spoke at the hearing. She and Ashby’s grandfather had raised Ashby and said they had seen no hatred in him.

She described a 14-year-old boy who cared for his tiny dog, played with his little sister, did his chores and told his grandmother he loved her.

But when the grandparents thought he was playing video games, he was being pulled into dark subject matter on the internet, she said. Others said he was groomed on the internet.

Ashby, who has been diagnosed with severe major depressive disorder, said he’s not the same person as the boy who was arrested near the beginning of the 2025-‘26 school year.

“I understand the fear, pain and uncertainty my actions caused,” and is overwhelmed with remorse, he said.

Hearing the teacher and other school representatives’ statements “hurts so bad,” he said.

He didn’t understand the severity of what he did when he was arrested, he said. He was hurting then, believing his life was a mistake, and that he was a burden to everyone, he said.

He had begun to research mass shootings when he was 13, he said, and eventually created ranked listings of them and found comfort in the pain and suicide of those who planned them.

He has attempted suicide multiple times and has cut himself as punishment for his thoughts, he said. He continues to think about suicide, he said.

“I don’t want to suffer anymore,” he said “I don’t want anyone else to suffer anymore from my actions.”

Ashby’s attorney Branden Landon argued for a shorter sentence, allowing Ashby to be released at age 18 or 19, when he could be reintegrated into society under supervision.

A release at 21 would be without supervision and no help integrating into society because the juvenile justice system would no longer have authority over him, Landon said.

Heart filled with hatred

But Benton County Prosecutor Eric Eisinger argued that Ashby’s heart was filled with hatred and that his ranking of shooters showed utter “depravity.”

He targeted Kamiakin to boost his own ego, the prosecutor said, pointing out that the planned shooting was not linked to any person he disagreed with but targeted the staff and students in general. His goal was to take lives so in his mind he would ascend to “a perverted place of greatness,” Eisinger said.

He said that Ashby had also shown interest in an elementary school, Amon Creek Elementary, which is in south Richland but part of the Kennewick School District.

He had done online searches for information about the school, visited it and taken photos of the surrounding area, according to a court document.

Eisinger said that if Ashby were released today, there is no reason he would not again plan a school shooting, given his obsession with them.

“It is clear you are suffering,” the judge told Ashby right before she read his sentence.

The court wants him to heal, but that is going to take a lot of work and a lot of time, she said.