The incident happened around 7:20 p.m. Friday, Dec. 16 in Port Jefferson.
He was operating a vehicle on West Broadway at the Port Jeff dock when he suffered an apparent medical emergency and drove into the water, Suffolk County Police said.
The man has been identified as Stuart Dorfman, age 74, of Plainview, according to police.
Detectives are asking anyone with information on this incident to call the Homicide Squad at 631-852-6392.
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