GWINNETT COUNTY, Ga. — A Gwinnett County mother is in jail for murder after police said her infant son died from fentanyl exposure.

Police said 30-year-old D’Brianne McMillan left her son unattended on Tuesday.

According to an arrest warrant, McMillan kept fentanyl “In the vehicle in proximity to the victim’s child safety seat, and in her bedroom with the victim, which ultimately led to a fatal fentanyl exposure.”

McMillan has been charged with first-degree murder.

According to the State Department of Public Health, four children died last year from fentanyl who were just two years old or younger. It was the most fentanyl deaths ever recorded for children that young.

State data also shows that 38 teenagers died from fentanyl overdoses in Georgia last year.

Johnson knocked on the door where the toddler died in Gwinnett County, but a family member who was home didn’t want to comment. Some neighbors said off-camera that the child’s death was heartbreaking for them and made them burst into tears.