Investigators named Erik Williams Jr., 20, as the triggerman who fired two shots on July 17 at DeAngelo Hudgins and Albert Gilbert.
Edwin Cruz, 21, is accused of driving the getaway car that sped away from the apartment complex where the shooting happened, investigators say.
Both are charged with murder.
Gilbert, 25, was hit in the stomach, but was still able to bang on doors and rouse someone to call for help at Sanctuary Apartments. Hudgins, also 25, was hit in the chest and died the next day at Eisenhower Army Medical Center at Fort Gordon, where he served as an MP.
The 9 mm pistol used in the shooting was the key to cracking the case, Capt. Scott Peebles said Thursday night.
Richmond County investigators were tipped off Wednesday by their colleagues in Columbia County that the weapon had been recovered in an unrelated case. Ballistics tests confirmed that it was the gun that killed Hudgins, according to a news release.
That tip led investigators Thursday to Williams' home in the 200 block of Sassafrass Lane in Grovetown, where both Williams and Cruz were taken into custody and brought to the sheriff's office for questioning.
They were later charged with murder, aggravated assault and possession of a firearm during the commission of a crime. Williams has an additional charge of possession of a weapon by a convicted felon.
Their statements also led to the arrest of five people who knew the identity of Hudgins' shooter, but are accused of lying about it to investigators, a news release states.
Peebles said investigators suspected all along that the five were withholding information and warned them several times about the consequences.
Those charged with making false statements in a government matter are: Trenee Johnson, 20, and Jasmine Johnson, 19, both of the 5000 block of Sanctuary Drive; Shardae Davis, 19, and Tony Davis, 18, both the 500 block of Wendover Ct.; and Crystal Pryear, 18, of the 1300 block of Wickham Court.
Peebles said Hudgins and Gilbert were in an argument earlier that evening with the five people. The two accused in the slaying went by the apartment complex later that night to check on their friends and more words were exchanged.
Two shots were fired and both hit their target, Peebles said.
Because of a reporter's error, Friday's edition of The Augusta Chronicle transposed the names of a man injured by gunfire in July, Albert Gilbert, and a suspect arrested Thursday, Erik Williams Jr.
The Chronicle regrets the error.