An autopsy confirmed that the death of a toddler at a New York City day care earlier this month was caused by fentanyl overdose.

On Sept. 15, Grei Mendez, 36, who operated El Divino Nio day care from an apartment in the Bronx, called the police to report that some of the children at her day care were unresponsive. The children were taken to the hospital and received treatment for what medical professionals determined to be symptoms of opioid poisoning.

One of the children, Nicholas Feliz-Dominici, was pronounced dead upon arriving at the hospital. The New York City medical examiners office confirmed on Friday that the 1-year-old died from acute fentanyl intoxication, CBS News reported .

During a search of the apartment, police found large quantities of fentanyl, including a kilogram of fentanyl stored on top of a childrens play mat, and machinery and paraphernalia used to package narcotics. In a further search, a secret compartment with large quantities of fentanyl and other drugs was found .

Mendez was arrested on federal drug charges in this case, and is also facing state murder charges . According to the Associated Press , three other people have been arrested on federal charges in relation to this case, including Mendezs husband, Felix Herrera Garcia, 34, who had fled the day of the incident.

Prosecutors say Mendez had called Herrera Garcia as well as another employee before dialing 911 on Sept. 15 to report the unresponsive children. Mendez allegedly also deleted about 21,526 messages between her and her husband dating back to March 2021 through an encrypted app.

Parents entrusted Grei Mendez with the care of their children, U.S. Attorney Damian Williams said in a statement . As alleged, instead of diligently safeguarding the well-being of those children, she and her co-conspirators put them directly in harms way, running a narcotics operation and storing deadly fentanyl out of the very space in which the children ate, slept, and played. The disregard shown by Mendez and her co-conspirators for the lives of the children under her care is simply staggering.