They said it happened just after midnight on U.S. Highway 70 at Ranch Road, near Clayton.
Authorities said a man posing as a police officer used a gun to rob his victim.
The victim called 911 after the incident and said the suspect, who was described as an African American man, forced him to hand over his laptop computer and cash.
He told deputies he wasn't aware of the 'Blue Light Bandit' nor investigators' advice to call 911 before stopping for an unmarked car in Johnston County.
It is the fourth reported incident in the past two weeks.
On Tuesday morning, a 49-year-old Benson woman said she was traveling westbound on Interstate 40 near the rest area outside of Benson when she was pulled over.
The woman said she stopped for a black man driving a dark colored Ford Crown Victoria with a flashing blue light. He approached the woman's car, told her she was speeding and asked for her driver's license and registration.
The sheriff's department said the suspect walked back to his vehicle, then after a few moments, returned and handed the woman her license and registration, then left the scene. The woman was not robbed.
The suspect was described as approximately 5' 6" tall and 130 pounds wearing a tan shirt and black belt.
The incident could possibly be linked to a similar blue light bandit case on March 25 on I-40 near McGee's Crossroads. Another incident was reported on April 6, on I-95 near I-40. However, the suspect in that case was a white male driving a blue or green Chevy car. Both of those cases involved the robbery of the motorist.
Deputies said they are ramping up efforts to catch the blue light bandit.
"All available measures are being taken to locate and apprehend this individual that is impersonating a police officer," said Lt. Jeff Caldwell, with the Johnston County Sheriff's Office.
Authorities have said if you are pulled over and have concerns that it might not be a real law enforcement office, immediately slow down, turn on your emergency flashers, and call 911.
Tell the dispatcher your exact location and a description of your car and the vehicle attempting to stop you. Proceed to a well-lit area and following the dispatcher's instructions.
A reward of up to $1,000 is being offered for information leading to the arrests and convictions of those responsible. Anyone with information is asked to call (919) 989-5000.