Authorities say a 27-year-old Lilburn man tried entering the courthouse with a Smith and Wesson handgun and ammunition in his backpack Jan. 31.
Charges against the unidentified man were later dismissed.
On March 13, a 35-year-old Tennessee woman was arrested after security officers found a pink Glock and ammunition in her purse.
Also on March 13, a 22-year-old Atlanta woman was arrested after security guards found a gun in her purse.
Authorities discovered the woman was also wanted in DeKalb County.
Authorities say another unidentified man who was arrested for carrying a gun into the county courthouse Wednesday has bonded out of jail.