A man and woman were arrested in Fairfield for possessing kilograms of fentynal in September, state police said.
State troopers stopped a 2017 Chevy Cruze traveling on Interstate 95 near exit 21 on Sept. 30.
Connecticut State Police said after speaking to the driver, Arianna Spencer, and passenger, Isaiah Roman, probable cause was developed and they were given permission to search the car.
A narcotics K-9 alerted police to something in the trunk and troopers found approximately five kilograms of suspected fentynal. Police also seized a small amount of cocaine in the center console.
Spencer and Roman were arrested and face possession and illegal drug sale charges. Spencer was also charged with speeding.
Their bonds were set at $500,000.