Marcus Darnell Richardson, 26, turned himself in about 3:30 p.m. and was being held without bond on charges of murder and possession of a firearm during the commission of a crime.
Investigators have linked him to the death of Eric Phillips, whose body was discovered Wednesday afternoon in a small park on Meadowlark Road. Another person, whose identity has not been released, is also wanted in connection with that slaying, which investigators said is drug-related.
That leaves three of the eight homicides in July without arrests.
The criminal investigation division added another full-time investigator to the homicide roster this week in an effort to catch the remaining killers.
The most recent unsolved homicide happened Sunday at Sanctuary Apartments, off West Wheeler Parkway in west Augusta. Two off-duty military policemen were shot by a gunman riding in a forest green 1989 Honda Accord about 3:30 a.m.
One of the men, Deangelo Rondelle Hudgins, 25, was shot in the chest and died the next day.
Friday afternoon, deputies with the crime suppression unit fanned out into the apartment complex to knock on doors and pass out fliers offering a reward for information.
Motorists passing by also were handed fliers, which included a picture of a car similar to the one used by the shooter. The car, which has a loud muffler and pop-up headlights, had been seen in the area several times, neighbors said.
The gunman was described as Hispanic, with curly brown hair and a thin mustache.
Residents of the apartment complex, who didn't want to be named out of fear of retaliation, heard several shots that night. Hudgins didn't move after he was shot, but the other victim, Albert Gilbert, ran down the street banging on doors and asking for help. He was shot in the abdomen.
Deputies taped fliers to the doors of people who didn't answer their knock, but the ones they talked to promised to help any way they could.
"Hopefully it will give us some leads," said Sgt. Ken Rogers. "But if not, we're still trying."