About Radius Investigations


Radius Investigations has established itself as a leading force in surveillance, insurance investigations, and security services; coupled with expertise in corporate due diligence and background investigations, litigation support, fraud, and internal investigations. Clients of Radius Investigations benefit from the most comprehensive, professional, and skilled investigative services available in New York, nationwide, and globally.

The experienced team of investigators, all bring a multi-disciplinary and diverse skill set and experience, ranging from retired law enforcement, legal practice, and military service. As a result, Radius Investigations approaches each case from differing but complementary viewpoints, which enables the firm to provide the highest quality investigative, due diligence, intelligence, and security consulting service available.

Radius Investigations provides assistance to law firms, large and small companies, religious institutions, advance business opportunities, mitigate risk, win or avoid lawsuits, and resolve disputes.

Our services include:

  • Litigation and Pre-litigation Intelligence and Investigations
    – White Collar
    – Commercial
    – Matrimonial, Divorce, and Child Custody
    – Financial
  • Missing Person Location and Witness Interviews
  • Surveillance
  • Asset Searches and Analysis
  • Internal Corporate Investigations
  • Audit and special Committee Investigations
  • Foreign Corrupt Practices Act and anti-money Laundering Investigations and Compliance
  • Business and transactional Intelligence
  • Due Diligence and Background Checks
  • Fraud Investigations and preventative Consulting
  • Hedge Fund Investigations
  • Intellectual Property, Counterfeiting, Piracy, and Technology Investigations
  • Subpoena Compliance consulting

Radius Investigations has a network of private investigators and sources throughout the United States and around the world, enabling the firm to assist clients wherever their issues may arise.


Matthew D. Seifer
Licensed Private Investigator, Executive Protection Specialist, Technical Surveillance Countermeasure Specialist

Matthew has been a self-employed business owner since his honorable discharge from the United States Army in October of 1990. In over 25 years of private sector experience, Matthew has earned a reputation for professionalism and integrity. As a result, he has established long-standing relationships with law enforcement, government personnel, the legal community, the insurance industry, and clients from all over the globe.

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. 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 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.

In addition to his extensive investigative skills, Matthew is a licensed armed guard in New York. He has extensive training and expertise in threat assessment, executive protection, event security, and premises security operations.


Matthew believes in volunteering his personal and professional time to the community. He has been a long standing member of the Lions Club International and has been honored with the prestigious Outstanding Leadership and Achievement Award from the Lions Club International President.

For more information about Radius Investigations, please feel free to contact Matthew at m.seifer@RadiusInvestigations.com,
or you can contact Matthew directly at 631-492-4000.

Ready to find out more?

For more information about Radius Investigations,

contact an investigative professional at info(at)radiusinvestigations.com,

or call us directly at 631-351-6479 or toll-free at 888-698-0077.

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