Investigators say Robert Bell,33, is considered armed, dangerous and currently on the run.
Bell is accused of murdering a 34-year-old woman, her 12-year-old son and 19-year-old godson. A fourth gunshot victim is expected to survive.
Investigators say that bell was living with the victims near Atlanta. The homeowner let Bell stay in the home as an act of charity.
Bell has a previous Chicago address and an address in Joliet. He has been arrested in Illinois multiple times.
"We're considering him armed and dangerous; we do believe we have recovered the murder weapon," said Jake Smith of the Gwinnett County Police Department. "We don't know what other weapons he might have access to."