A 14-month-old boy died after being exposed to fentanyl left near his car seat and in a bedroom, according to Gwinnett County police.

Investigators believe 30-year-old D’Brianne McMillan had both methamphetamine and fentanyl in her Lawrenceville-area home. She was arrested last week on several charges, including second-degree murder and cruelty to children, after the boy’s death, according to arrest warrants.

McMillan is accused of leaving Amir Blackwell unattended while he was near the illegal drugs, warrants state. The relationship between McMillan and the boy is not stated in the warrants, but the case has been classified as family violence.

“Said accused knowingly and unlawfully did possess fentanyl in proximity to the victim, 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, and leave the victim unattended,” McMillan’s warrants state.

McMillan was also charged with two counts each of meth possession and possession of drug-related objects, plus possession of a controlled substance, jail records show. She remained Thursday in the Gwinnett jail, where she was being held without bond.

The arrest was the second for Gwinnett police in a matter of days related to fentanyl deaths. On Aug. 7, a suspect charged with murdering two men who died from fentanyl overdoses was arrested in Atlanta, according to the Gwinnett Sheriff’s Office.

David Shane Lancaster, 45, of Lawrenceville, was a fugitive until his arrest. When he was found, he had a backpack that contained methamphetamine, a scale and a gun, investigators said.

Lancaster has been charged with two counts of felony murder and one count of sale of a controlled substance. The warrants for Lancaster were secured by Gwinnett police July 26.

According to the Atlanta-based Centers for Disease Control and Prevention, there are two types of fentanyl, pharmaceutical fentanyl and illegally made fentanyl, and both are synthetic opioids. It is the illegally made fentanyl most often used in overdoses, the agency said.

Drug dealers have been accused of mixing fentanyl with other drugs including heroin, methamphetamine and cocaine, according to the U.S. Drug Enforcement Agency. That increases the likelihood of a fatal interaction, the agency said.