Another daughter was with her parents when they were arrested, authorities said. She was placed in the care of the Georgia Department of Human Services.
Donald Boyd Harris and Allison Studdard face drug charges in Mississippi. Bryan Rickert, a police captain in Lowndes County in Mississippi, said additional charges depend on the outcome of an autopsy on their daughter, Alyssa, 7 months.
Investigators said Alyssa's grandfather, who shared the home near the Alabama border in northern Mississippi with Harris and Studdard, found Alyssa dead at about 5:30 a.m. Wednesday. While he was calling police, the couple left with their older daughter, Maliah, 2.
An Amber Alert was issued for Maliah. It was canceled after a police officer recognized Harris and Studdard and arrested them at a gas station in Sylvester in southwest Georgia.
Mississippi is seeking the couple's extradition.