After serving as a school principal, when the Sandy Hook Elementary School shooting happened, I knew I would have tried to protect my students, just like Principal Dawn Hochsprung was killed while trying to protect her students . Like educators across the country, I watched in disbelief – and then with a growing sense of responsibility. We had invested heavily in alarms, cameras, drills, and lockdown procedures, yet one painful truth remained: once a threat is already inside a building, most school safety systems are designed to notify or respond later, not physically intervene in the moment that matters most.
That realization stayed with me. I didn’t want to accept that educators and students were limited to hiding and waiting during the most critical minutes of an active threat. I began asking a different question: What if buildings themselves could help protect the people inside them? That question led me to bring together experts from education, law enforcement, chemistry,
engineering, and security to explore whether structural change – not just policy – could close that gap.
The result of that work became Crotega Safety Solutions, a security technology company focused on developing non-lethal, interior defense systems designed specifically for occupied environments like schools.
At the center of our approach is SentriZone™, a first-of-its-kind interior defense system created to help interrupt violent behavior inside a building without requiring staff or occupants to directly engage a threat. I often describe SentriZone as the school safety equivalent of fire sprinklers: once considered radical, now essential infrastructure. SentriZone rethinks how buildings can actively respond to human threats from within.
SentriZone deploys REPULS®, a revolutionary water-based chemical irritant developed specifically for indoor environments. Unlike traditional aerosols, REPULS is non-flammable, non-aerosol, and designed to avoid widespread contamination in classrooms, hallways, and common spaces. When activated, it causes immediate, temporary involuntary eye closure along with intense irritation to the eyes, skin, and respiratory system – disrupting a threat’s ability to see, move, or continue an attack. The goal is not punishment, but to deter, disrupt, and delay, creating critical time for people to escape, secure themselves, or await law enforcement. REPULS is also available in handheld formats, giving trained staff and safety personnel a portable, non-lethal option where fixed systems are not yet installed.
Together, SentriZone and REPULS provide schools with a non-lethal, interior defense option that aligns with the realities of active, occupied learning environments.
Practical steps schools can take to strengthen safety
● Plan for the minutes before help arrives, when interior intervention matters most and response time can determine outcomes.
● Add interior layers of protection, treating safety as part of building infrastructure, not just perimeter control.
● Prioritize solutions that don’t require direct engagement, so educators and staff aren’t forced into physical confrontation.
● Use non-lethal tools designed for occupied spaces, such as REPULS, which avoids aerosol spread common with traditional sprays.
● Design safety into the building itself with systems like SentriZone, which can help interrupt violent behavior from within.
● Coordinate safety planning with first responders, ensuring school-based systems support law enforcement response rather than complicate it.
We may never eliminate every risk, but we can continue to innovate in ways that give schools more time, more options, and more protection when it matters most.
Watch a demonstration of SentriZone with REPULS here: https://youtu.be/1ldpv4QkPoo?si=Il C6EfRaNxdn5Vx
Thank you,
Glenda, Charlie and David Cates
