65-year-old Steven Mayer of Great Neck went missing Oct. 4 on his way to his job as a metals trader in Huntington. His family had said he used anti-seizure medication.
Authorities found Mayer's car Saturday and discovered a body inside.
Riverhead town police said Sunday that the body has been identified as Mayer.
Autopsy results were pending.
Thousands of volunteers had combed the Riverhead area for Mayer using all-terrain vehicles, boats, planes and a helicopter.