One firefighter told deputies "they suctioned a lot of water from the child" as he was being transported to Piedmont Newnan Hospital, where he was later pronounced dead, according to Law & Crime.
Brantley's mother and owner of the home, 36-year-old Kelli Gordon, told investigators on the scene she had gone shopping and returned to find her daughter and grandson were in the upstairs bathroom, taking a bath.
She said she tried to check on them through the door several times "since she had been in the bathroom for some time," but only got mumbled responses that she couldn't understand, so she "went back to watching TV."
About ten or twenty minutes later, she was startled by a scream from inside the bathroom; she found Brantley holding the baby saying "he can't breathe, what do I do?'"
Gordon said she took her grandson and "began resuscitating him", telling investigators she "saw how blue he was, and he was cold, real cold."
According to the police report, the deputy then went to speak with Brantley, who was "sitting in a chair with only a towel wrapped around her crying" and "not in a state where she was willing to speak."
After executing a search warrant, police said they found methamphetamine at the home. They believe Brantley took some before getting into the bath with her son.
She was arrested on second-degree felony murder and second-degree child cruelty charges.
Gordon meanwhile was arrested and charged with possession of narcotics, The Newnan Times-Herald reported. Her five other children were also taken from her and placed in the care of the Georgia Department of Family and Children's Services.
Brantley was denied bond and remains in custody. Her mother is also still in custody on other charges, unrelated to either the drugs or the death of her grandson.