SAVANNAH, Ga. (AP) — Authorities in Georgia say a bystander who was killed in a police shootout with a suspect was the suspect's grandmother.

Georgia Bureau of Investigation spokeswoman Nelly Miles said Tuesday that forensic tests are still pending to determine who fired the shot that killed Cynthia Fields inside her Savannah home. A news release said Fields' grandson, 20-year-old Chantz Cooper, was charged Monday with aggravated assault, attempted armed robbery and possession of a firearm by a felon.

The bureau said Savannah police were investigating a nearby shooting Friday evening when they found Cooper, who matched the description of a possible suspect, on his grandmother's porch. Investigators say Cooper and an officer shot at each other and Fields was struck by gunfire.

It was not immediately known if Cooper had an attorney.