Autopsies performed by the Fulton County Medical Examiner's office indicate Sartaj Grover, 12, and his 5-year-old brother Gurtej died of sharp force injuries to the neck, The Atlanta Journal-Constitution reported Wednesday.
The death of the boy's mother, Damanjit Kaur-Grover, 47, was the result of blunt force injury to the head.
The autopsy report ruled the death of Sindiver Grover, 52, a suicide by hanging.
Neighbors in John's Creek described the Grovers as a happy couple.
Police would not speculate on which family member was responsible for the killings.