Vincent Stallings, 21, of Wilmington, Delaware, Andre D. Palmer, 25, of Fairburn, Georgia and Vanisha D. Carson, 25, of New Castle, Delaware are also charged with robbery and related counts.
Police say Stallings was the suspect who fired the shot that killed the clerk, 48-year-old Mohammed Rafique Ullah.
According to investigators, Carson drove Stallings and Palmer to the store at approximately 12:40 a.m. on Wednesday. Police say Palmer and Stallings entered the store wearing face masks - Stallings allegedly wore a black mask and Palmer wore a white mask.
The suspects confronted Ullah, police say, and demanded money. Ullah complied and turned over an undisclosed amount of cash.
As Stallings and Palmer were leaving the store, police say Stallings turned and fired at least one shot, hitting Ullah in the chest. He was pronounced dead at the scene.
Police earlier said there was no apparent reason for the suspect to fire. Ullah had moved to the U.S. to provide for a better life for his wife and 8-year -old son back in Bangladesh.
Through the investigation, police learned of a similar robbery three hours earlier at the I-95 service plaza in Newark. In that case, two masked men entered the rear door of the plaza, threatened an employee, and tried to force open a secure room where a safe is kept.
However, the robbery attempt was unsuccessful and the two fled in a getaway car, but not before a trucker at the plaza was able to get the license plate number of the vehicle.
That information, plus surveillance video of the attempted plaza robbery, led police to the apartment of Palmer and Carson on Wednesday. There, police say, they found a white face mask worn in both robberies.
Then, at 3:00 a.m. Thursday, police executed a search warrant at the Lancaster Court Apartments where they took Stallings into custody.
All three suspects have been ordered held behind bars while the investigation continues.