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Meet the Guardian 6 Team
Jon Teske
Principal Consultant
Lieutenant Colonel Jonathon Karl Teske has built a distinguished dual career in military service and public education, marked by more than two decades of leadership in the U.S. Army Reserve and nearly 30 years of dedicated service to the students and schools of Indian River County, Florida.
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Commissioned through ROTC in 1996, LTC Teske has served over 24 years as a Military Police officer. Throughout his career, he has held key leadership roles including platoon leader, executive officer, S2, MP team chief, senior CHOT, and ultimately Branch Chief within the 84th Training Command. His assignments have spanned both stateside and overseas operations, including mobilizations in support of Operation Iraqi Freedom and numerous training and security missions throughout the United States and abroad. He is a graduate of extensive military professional development programs, including the MP Officer Basic and Captains Career Courses, Observer/Coach/Trainer certifications, and the Intermediate Level Education program. His exemplary service has been recognized with multiple awards, including several Army Achievement Medals, the Armed Forces Reserve Medal with “M” Device, and the German Armed Forces Efficiency Badge (Gold).
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Parallel to his military service, Jon built an accomplished career in public education. Beginning as a classroom teacher, he progressed into school administration, serving 15 years as a principal before transitioning into district leadership as an Assistant Superintendent. He later assumed responsibility for districtwide safety and security, serving as Director of Security and School Safety Specialist. In this role, he oversaw all school threat assessment processes, managed physical security operations, and served as the primary liaison with local law enforcement and emergency response agencies. His expertise also extended to professional instruction, he has presented and instructed at the state level, including sessions at the Annual Florida School Safety Conference. He retired from the Indian River County School District in June 2025.
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LTC Teske holds a bachelor’s degree in Elementary Education from Newberry College and a master’s degree in Educational Leadership from Nova Southeastern University. His career reflects a lifelong commitment to public service, organizational leadership, and the safety and development of others, whether in the classroom, the community, or the military.
Sean Connolly
Principal Consultant
Sean Connolly is a retired Police Detective with 26 years of law enforcement service and over three years as an Armed School Security Officer. Based in Wallingford, Connecticut, he brings proven expertise in criminal investigations, threat assessment, crisis management, and executive protection. A U.S. Air Force veteran, Sean served in the Tactical Air Control Party (TACP) during the Persian Gulf War, directing close air support missions in combat zones. These experiences sharpened his ability to remain calm and decisive under pressure while coordinating with multiple agencies in high-stakes environments.
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Throughout his career, Sean collaborated with the U.S. Secret Service, NYPD, DEA, and NTSB on complex investigations and protective details. He has provided executive protection for dignitaries at Grand Central Terminal, supported counter-surveillance operations during the Republican National Convention, and worked security operations alongside federal partners during the United Nations General Assembly.
As President of the Fairfield County Detectives Association, Sean expanded training opportunities for detectives, organized intelligence-sharing conferences, and strengthened interagency collaboration across Connecticut. His technical expertise includes surveillance technology, covert camera deployment, crime scene forensics, and incident command systems. He is FEMA NIMS/ICS certified and trained in terrorism response, post-blast investigation, and crisis incident management. Sean continues to serve his community by leveraging decades of tactical knowledge, investigative skill, and operational leadership to help schools, organizations, and communities prepare for and respond to today’s evolving security challenges.
Brent Heidenis
Principal Consultant
Brent Heidenis is a retired U.S. Army Master Sergeant and Quality Assurance Officer with over 28 years of distinguished military service and nearly three decades of educational leadership and coaching experience. He served in Operation Iraqi Freedom in a logistics role and in Operation Joint Endeavor in Bosnia, where he specialized in security operations. These assignments equipped him with extensive expertise in organizational management, operational safety, and secure mission execution.
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In his final military assignment at the Regional Training Institute, Brent served as Chief Instructor, leading the cadre responsible for Officer Candidate School and Combat Medic training. As the Regimental Quality Assurance Officer, his leadership was instrumental in achieving two “Institute of Excellence” ratings during TRADOC accreditations—national recognition of the highest standard in military training and instruction.
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Brent’s dedication to service extends beyond the military into education. As a teacher and coach, he brings an inside perspective on school safety, classroom operations, and athletic event management. His ability to assess situations, anticipate challenges, and develop structured, adaptable plans makes him a trusted voice on his school’s safety planning committee. Valued for blending military precision with educational insight, Brent continues to apply his skills to strengthen safety, preparedness, and leadership in both academic and community settings.
Thomas DaCosta
Principal Consultant
With 27 years in law enforcement and a decade of service in the U.S. Marine Corps, Thomas DaCosta brings exceptional tactical expertise, operational leadership, and strategic foresight to the field of security consulting. Rising to the rank of Deputy Inspector and Transit District Commanding Officer with the New York MTA Police, he led more than 70 officers in safeguarding the nation’s largest transit system. His career included high-profile assignments with the U.S. Secret Service and ATF, where he contributed to the security of the 2004 Republican National Convention, the 2008 visit of Pope Francis, multiple United Nations General Assemblies, and large-scale events at Yankee Stadium. As a Police K9 Handler specializing in explosive detection, Special Reaction Team operator in the Marines, and Field Training Officer, Thomas has consistently demonstrated the ability to lead under pressure and protect both dignitaries and the public during high-risk operations.
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Certified in Crime Prevention Through Environmental Design (CPTED) and trained through FEMA’s National Incident Management System and Incident Command System, Thomas integrates environmental planning, crisis response, and interagency collaboration into his approach to safety. He is certified by the New York State Department of Criminal Justice and the Connecticut Police Officer Standards and Training Council, and has completed advanced leadership training through the FBI LEEDA Trilogy, FBI Command College, and FBI National Academy Leadership Symposium. Currently completing his Bachelor of Arts in Organizational Leadership, Thomas now applies his extensive experience to consulting, delivering tailored security solutions that empower organizations to navigate today’s complex threats with confidence and integrity.
Brien McMahon
Principal Consultant
Brien McMahon is a seasoned law enforcement professional with over 25 years of service at the Milford Police Department, where he currently serves as a Detective. His career spans investigations in fraud, robberies, and other major crimes, as well as specialized assignments in undercover operations, surveillance, and tactical narcotics enforcement. Working closely with state and federal agencies, Brien has led and supported high-profile operations resulting in major narcotics and money seizures, while also contributing to organized crime investigations. His service in the Marine Unit further broadened his expertise, with responsibilities ranging from anti-terrorism patrols to underwater recovery operations as a certified scuba diver.
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Recognized with a Meritorious Service Medal, 10 Commendation Ribbons, and 13 Unit Citations, Brien has built a career defined by professionalism, courage, and technical expertise. He holds a Bachelor of Science in Sociology/Criminal Justice from Southern Connecticut State University and maintains numerous certifications in firearms, emergency medical response, and advanced surveillance techniques. At Guardian 6 Consulting, he applies his deep investigative knowledge, crisis management skills, and leadership experience to support schools, municipalities, and organizations in strengthening safety and security.
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