State Police responded to a tractor-trailer on the shoulder of the Sagtikos Parkway southbound at about 3:15 p.m. on Tuesday, Sept. 28.
Police said the vehicle was north of Exit S4 in the Suffolk County Town of Islip.
The driver, Rafael Velasquez, of Texas, was found in possession of the handgun without a New York pistol permit, police reported.
He was arrested and charged with second-degree criminal possession of a weapon, State Police said.
He was scheduled to be arraigned on Wednesday, Sept. 29.
The Suffolk County Police Department assisted with the investigation.
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