MEMPHIS, Tenn. — The mother of the girl charged with second-degree murder in the overdose deaths of two Fayette County teens died on Sunday, officials say.

Fayette County Chief Deputy Ray Garcia said the woman, who has not been named, was rushed to the emergency room in Collierville.

The cause of death is not yet known. Investigators are working with Collierville Police to determine if her cause of death was related to an overdose.

The woman’s daughter was the lone survivor of the overdose incident, which happened hours before the graduation at Fayette Ware High School on May 16.

“It’s a very tragic situation dealing with these teens first of all,” Fayette County Chief Deputy Ray Garcia said. “And now that we have a possible other family member that’s tied into this, it goes to show the potential dangers surrounding the drugs that are out there on the street nowadays, how powerful they are and how much damage and devastation they can cause in one community.”

During a hearing last week, a narcotics investigator with the Fayette County Sheriff’s office testified that fentanyl was found at the high school, where the girls died. The drug was also found at a home, after a search warrant.

According to investigators, they looked through text messages and social media and were able to find evidence to assist with the case.

The judge decided to release the girl into the custody of her grandmother.