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Long Island Private Investigator

LI Private Investigations
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(516) 203-4411
199 Willis Avenue
Mineola, NY 11501
North American Investigations is Long Island’s leading industry expert in the private investigation field. Our firm offers an array of services, including surveillance, matrimonial/infidelity, criminal, missing person investigations, and background checks. We understand what our clients are looking for and know how to deliver the best results possible. NAI is here to bring you peace of mind.

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private investigator long island

NAI’s Long Island private investigators are here to help assist you in your time of need. With over 45 years in business and thousands of cases solved, we are the leading industry experts here to help you obtain the evidence needed in your investigation. Headquartered in Mineola, New York, we are licensed and bonded, with a reputation and history that surpasses our competitors. We understand New York State’s laws and regulations, and take great pride in always conducting legal and ethical investigations.

Our LI private investigators serve both Nassau County & Suffolk County, and are trained to handle suburban, urban, and rural investigations. All cases are performed by our most professional and experienced staff members, including retired police officers, former narcotic investigators, detectives, and licensed private investigators. We utilize a variety of private detectives (both male and female of multiple ethnicities), allowing us to adapt to any environment or situation.

Our investigators always deliver the facts from an objective standpoint. We pride ourselves on our moral character and high ethical standards, consistently delivering the evidence to prove it. Observation and obtaining evidence is critical in our field, and all clients receive a report of our findings that is suitable for court along with video or photo documentation. Our video and photo evidence is time and date stamped, allowing you to know that you are being delivered accurate results by professionals. This supports and corroborates the investigator’s observations, which can be utilized in the court of law for any legal situation. We are able to provide court testimony and have expert witnesses available as needed.  Our private investigators on Long Island provide an array of services.  Our most popular include:

-Matrimonial, Alimony, & Divorce Related Investigations
-Child Custody Investigations
-Insurance Fraud
-Background Checks
-Locate Investigations/Missing Persons

Locations of our Private Investigators

Nassau County

Brookville, Floral Park, Garden City, Glen Cove, Great Neck, Hempstead, Mineola, Muttontown, Old WestburyPort Washington, Sands Point, Sea Cliff, Valley Stream, Williston Park, Woodbury

Suffolk County

Amityville, Belle Terre, Dix Hills, East Hampton, Huntington, NorthportPatchoguePort Jefferson, Smithtown, Southampton, Riverhead

Contact an LI Private Detective Today:

By hiring LI Private Detectives at NAI, you are in safe hands with a reputable business that has an A+ rating with the BBB. From the moment you call, our primary goal is to help you find peace of mind – from the free consultation to the moment you receive our report findings. The goal of all of our investigations is to provide our clients with the truth, always being accurate, diligent, discreet, and impartial. Unlike our competitors, we are a fully staffed agency, enabling us to handle a vast array of investigative needs. Start now by calling for a free consultation with our chief investigator.


Long Island Private Investigator

(516) 203-4411


Reliable, Sensitive, and Sensible


We have worked with North American Investigations for more than a decade and have found them to be reliable, creative, sensitive, and sensible about the expense necessary.

by Kenneth Koopersmith from Law Offices of Kenneth Koopersmith, LLC