Expert New York City Private Investigators
Private Investigation Services Throughout the Five Boroughs
Available 24/7
Matthew Seifer founded Radius Investigations in 2007. Seifer has an extensive background in private investigations and security, with over a decade of experience in these industries. Seifer is a U.S. Army veteran, with over 26 years in the private sector. He 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 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.

Mr. Seifer is described as strong and a born leader, as well as compassionate, dedicated, trustworthy, and diligent with his clients, students, and community. With his expertise and network of professionals, he can ensure that your needs will be answered anywhere in the world at anytime. He oversees every case and will follow through until the client has the answers they need to make an educated and informed decision.

See What Our Expert NYC Private Investigators Can Do. Here are a few of our many specialty services:
Corporate Investigations

Matrimonial Investigations

Child Custody Investigations

Missing Persons Investigations

Criminal Investigations and Litigation Support

Surveillance and Undercover Investigation

Computer, Smartphone, and iPhone Forensics

Social Media Investigations

Bug Sweeping (TSCM)

Data Retrieval and Acquisition

Digital Evidence and e-Discovery

Cyberbullying / Harassment Investigation

Personal Background Checks

Employee Background Checks

Business Intelligence

International Investigations

Nanny Background Checks

Caregiver Background Checks

Tenant Background Checks

Security Threat Assessments

Private Security Services


Aerial Drone Surveillance

Stalking and Harassment Investigation

Threat Investigation

Why Choose Radius Investigation’s NYC Private Investigators?
Simple. We Are “No Bull”:
We are here to find answers, not take you for a ride. We set ourselves apart from the rest with these four simple rules:
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