Alton Clay Brown, 39, was arrested July 15 by the Williston Police Department and charged with the July 14 murder of Clarence Weathersbee, 48.
Other charges may be pending, Investigator Rodney Pruitt said.
Testimony from witnesses varies, but Mr. Weathersbee was either entering or leaving the IGA General Food Store about 6 p.m. when he was shot in the lower torso, Investigator Pruitt said.
Mr. Brown is believed to have been waiting in the parking for Mr. Weathersbee, said Williston Police Chief Roger Kaney.
Mr. Weathersbee was pronounced dead at the Medical College of Georgia Hospital at about 8:45 p.m., Investigator Pruitt said.
Mr. Brown told police he and Mr. Weathersbee were involved in a fight earlier that day, Investigator Pruitt said.
Mr. Weathersbee's wife of 24 years, Charlene, said her husband was not only friends with Mr. Brown but the two also grew up together.
"They were friends - that's what hurts," Mrs. Weathersbee said.
She said she is looking to her children and other family for strength in coping with her husband's death.