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Matthew Seifer founded Radius Investigations in 2007. Matthew 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 and is not your typical PI. Matt’s work in security and education has made him evolve into not just a private investigator, but an instructor and mentor to help provide safety and security to the public. Matthew Seifer 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.

Matthew 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 County Criminal Courts, he is key in assisting clients during litigation cases. Matthew 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. Matthew’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 Radius Investigations can respond to our clients’ needs anywhere in the country.

Matthew Seifer is Radius 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 may intrude on our clients’ privacy, including GPS trackers, hidden cameras, and “bugs” or hidden recording devices.
Matthew is described as strong and a natural born leader, as well as compassionate, dedicated, trustworthy, and diligent with 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 Radius Investigations, he has expanded the agency from his Long Island, New York headquarters to New York City and Brooklyn in addition to developing a worldwide network of private investigators. Matthew’s professional expertise has made Radius Investigations 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 their new training division, Guardian Security Training.