Guardian Security Investigation & Training, previously named Guardian Investigations, centrally located on Long Island in Deer Park, NY, was formed in 2007 by Matthew Seifer, a Licensed Private Investigator, Registered Armed Guard, and Division of Criminal Justice Services (DCJS) Certified Instructor.
We have established ourselves as a leading force in surveillance, insurance investigations, workers comp investigations and security services; coupled with expertise in corporate due diligence and background investigations, security consultation, litigation support, fraud, and internal investigations.
Our firm has an experienced and diverse team of investigators, ranging from retired law enforcement, legal practice, and military service, available in New York including all of NYC and Long Island, nationwide, and around the world.
You can expect nothing less than sensitivity, confidentiality, thoroughness, expertise, professionalism, and integrity in services from Guardian Investigations. We take great care and pride in our cases. We do everything possible to reach a resolution to your case.
Guardian Investigations helps law firms, companies, religious institutions, and individuals solve problems, advance business opportunities, mitigate risk, win or avoid lawsuits, and resolve disputes.
Guardian Security Training provides New York State approved security guard training courses for Long Island and NYC. GST is the only training facility on Long Island to offer not only security guard courses, but private investigator development, HR218, conceal carry courses, and active shooter response seminars and drills.
Our mission is simple: to provide high quality education to build up qualified candidates, resulting in quality protectors for our community.
Licensed Private Investigator
Registered Armed Guard
Technical Surveillance Countermeasure (TSCM) Specialist
Expert Criminal Defense Investigator
NYS DCJS Certified Instructor
Matthew D. Seifer founded Guardian Investigations in 2007. Matt has an extensive background in private investigations and security, with over a decade of experience, earning him a reputation for professionalism and integrity. He is a U.S. Army veteran with over 26 years in the private sector. Matt is not your typical PI, his work in security and education has made him evolve into not just a private investigator, but an instructor and mentor who helps provide safety and security to the public. He has been featured on local and national media platforms, including Inside Edition, for his work in providing active shooter response training and drills for schools and the workplace.
Matt has been responsible for handling a wide variety of sensitive and complex investigations, including covert surveillance, undercover investigations, locating missing persons (including witnesses and adversaries for service of process), and securing key evidence for trial preparation. As an Expert Criminal Defense Investigator for the Nassau and Suffolk County Criminal Courts, he is key in assisting clients during their litigation cases.
Matt is also an accomplished investigative case manager and leader for teams of expert investigators. He has a great deal of expertise in assembling and managing teams of specialists representing a wide array of investigative skill sets in order to pursue the clients’ objectives in the most efficient and effective manner possible. Matt’s investigative support teams include retired law enforcement, military personnel, computer forensics experts, and counter-surveillance specialists.
Matthew has developed a network of specialized investigators in all 50 states in order to ensure that Guardian Investigations can respond to our clients’ needs anywhere in the country.
Matthew D. Seifer is Guardian Investigations’ counter-surveillance and technical surveillance counter-measures (TSCM), or “bug sweeping,” expert. He leads the firm’s operations in searching for, identifying, and neutralizing all forms of covert surveillance which could invade on our clients’ privacy, including GPS trackers, hidden cameras, and “bugs” or hidden recording devices.
Matt is described as strong and a natural born leader, as well as compassionate, dedicated, trustworthy, and diligent with all his clients, students, and community. He oversees every case and will follow through until the client has the answers they need to make an educated and informed decision.
Since the inception of Guardian Investigations, he has expanded the agency from his Long Island, New York headquarters to New York City and has developed a world-wide network of private investigators. Matthew’s professional expertise has made Guardian Investigations into not your typical PI agency.
We provide a broad spectrum of services including background investigations, TSCM bug sweeps, insurance investigations, as well as unique educational programs on security, safety, and private investigations through our new training division, Guardian Security Training.
Our quality professional instructors come from a range of backgrounds: Private Investigations,Law Enforcement, Federal Agents, and Military.
Jason Green has an exhaustive list of experience and accolades too long to list in a quick biography. A summary of his work includes over two decades of firefighting and Emergency Medical Technician (EMT) experience. Mr. Green has several instructor certifications, including fire service, NYS DCJS Instructor certifications in general topics, as well as law enforcement training and active shooter response training.
As a member of the Law Enforcement Trainers and Educators Association, Mr. Green emphasizes quality education for those who serve in law enforcement, as well as the general public in matters of proper safety and security procedures.
Green’s specializes in providing instruction for armed security training, LEOSA HR218, Handcuffing and Aerosol Restraint training, and unarmed security guard courses.
Lion’s Club International is a long-standing organization that works with local communities and charities in providing service and support. Matthew has been a member since 2002 and was honored with the prestigious Outstanding Leadership and Achievement Award from the Lions Club International President. Matthew Seifer’s project work included operating as 2nd VP of Canine Companions for Independence for the Northeast region.
The CHAIN (Charity, Humility, Autonomy, Integrity, Networking) is a professional networking association that focuses on connecting with other professionals through service and charity. Matthew Seifer and Guardian Investigations has worked with The CHAIN to raise money and participate with Habitat for Humanity and Bikes for Kids
LIPOD is a network directory of professionals with expertise in their industry located on Long Island. Matthew Seifer and Guardian Investigations are listed in their directory as the key experts in private investigation.
Guardian Investigations is a member of Island Business Affiliates (IBA) as the private investigator expert in their network. IBA is a local professional network providing trusted resources for the community’s needs.
Michael Magro Foundation, established in honor of Michael Magro, who lost his life to leukemia, provides awareness, advocacy, and support for families of children with cancer. Seifer participates and sponsors their annual “Evening of Tasting and Giving” event and is a member of 333 STRONG.
Long Island Networking Executives’ mission is to provide business relationships with other businesses and share knowledge from each member’s respective field. Matthew D. Seifer is the trusted representative for private investigation and security.