The events of May 7, 2019, didn’t just break a school; they fundamentally altered the way people in Highlands Ranch, Colorado, look at their own neighbors. When you talk about Devon Erickson and Alec McKinney, it is impossible to separate the names from the tragedy at STEM School Highlands Ranch. It was a day of graduation preparation, the kind of Tuesday where seniors were watching "The Princess Bride" and thinking about the summer. Then the doors opened.
Most people know the basics. One student died. Eight were wounded. But the narrative that emerged in the courtroom years later was way messier than the initial news reports suggested. Honestly, the details that came out during the trials revealed a toxic cocktail of drug use, mental health crises, and a "victim-hero" plot that sounds like something out of a twisted movie script.
The Motive Nobody Expected
For a long time, people wanted a simple reason. Was it bullying? Was it just pure malice? Alec McKinney, who was 16 at the time, eventually told investigators he’d been planning the attack for weeks. He was targeting specific classmates. McKinney, who is transgender and identifies as male, said he wanted the students who mocked his gender identity to "experience bad things" and "suffer from trauma" like he had.
Devon Erickson’s role was always the more debated part of the equation. He was 18, an adult in the eyes of the law, which changed everything for his sentencing later. Erickson’s defense tried to paint him as a puppet. They argued he was pressured, that he was sick, and that he was basically held hostage by McKinney’s plan.
But the evidence showed something else.
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The two of them didn't just walk in on a whim. They spent the morning of the shooting doing cocaine at Erickson’s house. They used an ax to break into a gun safe belonging to Erickson’s parents. They even tried to set a car on fire before heading to the school with a guitar case and a backpack full of weapons. You don't do all that if you're just "caught up" in the moment.
What Happened in Room 107
The shooting itself was over in minutes, mostly because of the sheer bravery of the students inside. This wasn't a situation where everyone just waited for the police.
- The Entry: Erickson and McKinney entered Room 107 through separate doors to maximize the chaos.
- The Confrontation: Erickson pulled a handgun from the guitar case. He reportedly yelled for nobody to move.
- The Sacrifice: This is where Kendrick Castillo comes in. He didn't hesitate. Kendrick, along with Joshua Jones and Brendan Bialy, charged Erickson.
- The Result: Kendrick was fatally shot in the chest. His actions, however, pinned Erickson and gave others the chance to subdue him.
Meanwhile, McKinney was firing a revolver on the other side of the room. He eventually ran out of ammunition and tried to turn a gun on himself, but he couldn't get the safety off. A private security guard eventually apprehended him in the hallway.
The Trials and the "Victim-Hero" Plan
One of the weirdest details to come out of the court proceedings was the "victim-hero" scheme. McKinney testified that they had faked videos of him "bullying" Erickson before the shooting. Why? So that if they got caught, Erickson could claim he was a victim who was forced into the act. They wanted to build a defense before the crime even happened.
The court didn't buy it.
In June 2021, a jury found Devon Erickson guilty on all 46 counts. Because he was 18 at the time of the shooting, he didn't get the leniency afforded to juveniles. He was sentenced to life in prison without the possibility of parole, plus an additional 1,282 years. It’s the longest sentence ever handed down in the 18th Judicial District of Colorado.
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McKinney’s situation was different. Because he was 16, he was eligible for a program for juvenile offenders. He was sentenced to life with the possibility of parole after 40 years. During his sentencing, he actually apologized to the victims, saying he didn't deserve forgiveness. It was a sharp contrast to Erickson, who remained mostly silent and showed very little emotion throughout his trial.
Where Things Stand Now in 2026
It has been several years since the sentencing, but the legal ripples are still moving. Just recently, in late 2025, the Colorado Court of Appeals made a major ruling regarding a civil lawsuit filed by Kendrick Castillo’s parents. The Castillos had sued the STEM School, wanting a trial to uncover exactly what went wrong with the school's security and why the warning signs were missed.
The court ruled that a full trial wasn't required because the school agreed to pay the maximum damages ($387,000) allowed under the Claire Davis School Safety Act. The Castillos aren't happy with that; they want accountability, not just a check. They’ve signaled they’ll take it to the Colorado Supreme Court.
Actionable Takeaways for School Safety
While the story of Devon Erickson and Alec McKinney is one of tragedy, it has pushed several hard conversations to the forefront:
- Anonymous Reporting Works: There were reports of an anonymous parent warning the school board about potential violence months before the shooting. Taking these tips seriously is the difference between prevention and disaster.
- The "Loner" Myth: Neither Erickson nor McKinney were total outcasts; they were students with social circles. The idea that you can "spot" a shooter based on a specific look is often wrong.
- Safe Storage: The weapons used were taken from a home gun safe. High-quality, biometric, or heavy-duty safes are essential, especially when there are troubled teens in the house.
If you are a parent or educator, the best next step is to review the threat assessment protocols in your own district. Most states now have programs like "Safe2Tell" where students can report concerning behavior anonymously. Encouraging a culture where "snitching" is seen as "saving" is the most effective tool schools have right now.