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Radius Investigations

The Absolute Experts in Private Investigations:

Radius Investigations is a full service private investigations company that provides the most efficient investigations. Located in Long Island, New York, close to Manhattan, NYC area as well as Brooklyn, Bronx, Staten Island and Queens. We are comprised of a team of elite Private Investigators with years of experience and resources all over the world. Our utmost dedication is directed towards making sure that our clients receive the highest quality of investigation services by providing you logical solutions to any unanswered questions you may have. We specialize in : Surveillance, Matrimonial Investigations, Theft of Intellectual Property, corporate Due Diligence, Background Checks and Criminal Defense. Our services are equally open to a vast range of clients that includes: private clients, law firms (regardless of the size and specialty), multi-national companies, financiers, hedge funds along with religious institutions.

This private investigation company consist of only professionals that are licensed, bonded and insured to execute investigations and surveillance in New York, the United States and Internationally. Our clients have always been comfortable with the fact that our private investigation firm maintains absolute discretion and confidentiality starting from the moment we are first contacted. Whether you contact us on our 24/7 phone lines or are requesting a consultation through our website, rest assured that your information is kept classified and confidential.


All the services that we offer have a success rate way beyond our competitors.

Here mentioned are only a few of our specialties:

*Investigations that we conduct are: Corporate, Matrimonial, Child Custody, Missing Person, Criminal and Litigation Support, Surveillance and Undercover Investigations.

*Technology Forensic services include: Computers, Smartphones, iPhones, Tablets, Social media investigations, Bug sweeps (TSCM), Data retrieval and Acquisitions, Digital evidence, e-Discoveries, along with Cyber bullying and Harassment Investigations.

*Accurate Background Checks for: Personal background, Employee background, Business Intelligence, International Investigations, Nannies, Caregivers and Tenants as well.

*Insurance Investigations are: Workman’s Compensation, Insurance Fraud and Accident Scene Investigations.

Our Promise

We will proactively find what you are seeking.

These four simple ways are what distinguish us from others:



The minute we are contacted by you, we provide top-quality services from licensed private investigators that deal with the facts. We do not run or hide, we work with you every step of the way, in getting you the intelligence you need. We are available 24/7 to assist you and answer any questions that you may have about your case.




During our work process you are involved and kept up-to-date throughout your whole case. We do not hide anything from you nor do we conduct any work without your approval first. Everything from the work to be performed to the cost of the case is clearly laid out nothing…



We take on the military philosophy of never giving up and working as one team throughout your case. Our team works vigorously work day and night, utilizing all of our resources to ensure that our clients receive the information that they need in order to make a decision.



Our concern towards your search for answers will never leave you feeling less than top priority. When you speak with us, we listen intently to understand your situation and give you the best possible advice and strategies for your case, based on the revealed facts.

Lead Investigator

Lead Investigator

Matthew Seifer is the founder, owner and lead investigator of Radius Investigations. He’s is a U.S Army Veteran, with over 26 years on 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 to help 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.

Matthew Seifer is described as a strong and natural 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 any time. He oversees every case and will follow through until the client has the answers they need to make a logical educated and informed decision.

Learn More about Matt Seifer’s Expertise, Work, and Community Involvement

Client Testimonials

  • Radius Investigations has provided service to me and my clients nationwide for several years, with impeccable and responsive service and excellent contacts and field work. I have been impressed with the nationwide contacts and level of service and recommend them highly. They are my go‐to investigators.

    -Cris Armenta, The Armenta Law Firm

  • I hired Matt Seifer several times and all times he produced results in a timely manner and the results were extremely thorough and detailed. My Privacy was kept just that, private. I would highly recommend Matt Seifer for your business, legal and personal matters. I can be contacted for further details.

    -David Esposito Entrepreneur, Business Professional

  • These guys are amazing. Quality professional service at an affordable price. As an attorney, time and time again I’ve turned to Radius in desperate situations where I needed a quality investigator to immediately help me locate someone, or get papers served in a timely and no nonsense manner, and they have never let me down. I highly recommend them to anyone who needs an investigator they can trust to get the job done!

    Joseph R.

  • Matt was the first to answer my request in finding “my sister”. He told me I had the “key ingredients” (a lot of information) for a search, and that he would refer me to someone in Pennsylvania as his business is in New York. He made a contact while I was on the phone with him and asked the PI in PA to give me a call and the reason why he should contact me. I very much appreciated his time and his concern. I believe our conversation covered all the pertinent details in about ten minutes. Thanks, Matt!

    Rita Y

  • Matt is one of the best PI’s I have worked with. I get excellent results from his investigations that I have used to obtain a fair and reasonable settlement. He is very creative when it comes getting information on a subject. I highly recommend his services.

    -Lory Metka

  • Outstanding investigative services, communication and resources! Great working knowledge and skill sets!

    -John Temblador

  • Even though I am experienced investigator, I rely on Radius for anything that happens in NY. They have quickly and more important, accurately supported my cases when it moved into the NY area or I needed a knowledgeable local investigator to gather documents

    -Gordon Adkins. Private Investigator

  • Outstanding investigative services, communication and resources! Great working knowledge and skill sets!

    -John Temblador

  • Even though I am experienced investigator, I rely on Radius for anything that happens in NY. They have quickly and more important, accurately supported my cases when it moved into the NY area or I needed a knowledgeable local investigator to gather documents

    -Gordon Adkins, Private Investigator

  • I knew going in that the answers I was looking for would be close to impossible to get without going through the court system. Erin was not only very professional, but also very emphatic and talked to me as a friend and not just a client whose money she wanted. I hired another PI before RI, and they didn’t even put 1/8 of an effort as Erin did to help me. I was kept in the loop throughout the process and never felt like my case was being ignored. I would highly recommend working with Radius Investigation for your next project especially if you’re working with Erin.

    -John S.

  • As the owner of a security business installing surveillance and burglar alarm systems I had the pleasure of meeting Matthew. I can honestly tell you that over the past 7 years I have known him that he is a man that stands behind is word and is a true professional at what he does.

    -Stephen Federlein, Infrastructure Specialist at Festo - Doom Inc.

  • From my first contact with the people at Radius, they were extremely respectful and professional. They were able to explain to me exactly what they were going to do to help me and told me how much it would cost. Even better, they stayed under my budget and finished sooner than I had expected. I have spoken with many investigative firms in the past and will continue to go back to Radius if I need investigative services again. They were excellent in every way.

    -Aviva M.

  • I have retained Radius Investigations to perform various investigative work. They always go above and beyond. I would recommend Radius to anyone or any entity that requires the assistance of a private investigator.

    -Gary R.

  • I spoke with Matt the week after Thanksgiving about locating my car. While he wasn’t able to help, he was a kind voice of direction in a sea of rude and unhelpful local police officers. Months later he followed up with me to find out if the vehicle was ever located. Thankfully it was. I am thankful for the kindness and compassion showed.

    -Sheila L.

  • I have worked for, and alongside Matthew Seifer for seven years and know him to be an intrepid investigator, who is thorough and professional. He has a broad range of experience and solid technical skills. Matt is ethical, conscientious and responsible in all matters of security matters and investigations.

    -Richard E. Duggan , AHFI Fraud Investigator at Verisys Investigations Inc.

  • I’m someone that was been involved with Law Enforcement for over 25 years including a career with the NYPD as a front line supervisor as a Sergeant in the NYPD. I can tell you from firsthand experience, both personal and professional dealings with Mr. Seifer, he is a true professional in his field, however he has a great asset that is truly lacking out there lately, that is… “Honesty & Integrity”. If he promises you something he delivers! He is always prompt, courteous, and highly competent to handle any task he’s given. He can be trusted with the most sensitive of issues to the most routine.

    Larry Boritz - New York State Regional Director at United Studios Of Self Defense

  • I will start with a conclusion – the job was done successfully! I have never dealt with private investigators, and i am glad i met a professional with a caliber of a person like Matthew – easy to deal with, comforting, professional, provided real solution and alternatives. My case was related to the divorce and all the investigation was legit and useful. Prompt, trustworthy, responsive, and importantly reliable. Thank you for your help!

    Hasan S.

  • Amazing job Way Beyond the Call of Duty highly recommended

    Ralph A.

  • Mr. Seifer provides a very professional, trustworthy service and is very knowledgeable in his field. He goes above and beyond to accommodate his clients to get the best results.

    Lisa Martelloni -Product Management Engineering - Max Mobilcom

  • Radius Investigations went the extra, extra mile for me trying to locate the executor and beneficiary of my fathers estate. Heart broken, I was pretty down after a month of searching and effort but he answered my prayers and found my brothers son and my brother ONLY BECAUSE he went the extra mile for me. As a life long Deep Sea – Merchant Mariner and seven year Veteran active service of the USCG and USN and 17 years USNR – this is not BS. I do not BS. I totally endorse Radius Investigations. Thank You Mathew.

    Bob Kuskis - First Officer - U.S. Navy Military Sealift Command

  • Great efficient service, definitely would use them again. Thank you Carmen and Matt!

  • Matt and his team at Radius were true professionals. They were prompt, courteous, and thorough from the first phone call and in every interaction. I felt comfortable working with them, and have great confidence in the Radius team. Matt was also honest in advising me when he felt spending more money would (or would not) be worthwhile. I’m glad I could trust their integrity and experience. I will absolutely call Radius again in the future, if the need arises.”