MOUNT HOLLY — As fentanyl keeps turning up in more and more drugs, addicts are being warned that what they don't know could kill them.

In this case, what a Lumberton woman didn't know ended up killing her baby.

The 34-year-old woman was sentenced this week to four years in prison for killing her 13-month-old son Jerimiah after taking drugs and passing out on top of him.

She admitted drinking alcohol and taking Percocet pills, which were laced with something far worse than fentanyl.

King said she had no idea that the pills she bought contained carfentanil, which is the most potent synthetic opioid that is used commercially. The opioid analogue can be 10,000 times more powerful than morphine and 100 times more powerful than fentanyl, which has been responsible for an uptick in opioid-related and cocaine deaths in recent years.

After King passed out on Jan. 19, she fell on her son and suffocated him. Police found both of them unconscious.

Antoinette King pleaded guilty in July to second-degree child endangerment.

Antoinette King was charged with accidentally killing her baby. (Burlington County Prosecutor's Office)