Updated September 25, 2023 at 8:33 PM ET

The operator of a New York City day care, a relative and an associate are facing federal drug charges after a 1-year-old boy died and three other children became dangerously ill, apparently from opioids: a one-kilogram brick of fentanyl was found stored inside the day care.

Grei Mendez, 36, who operates Divino Niño Daycare in the Bronx, was arrested earlier this month along with Carlisto Acevedo Brito, 41, her husband's cousin who was renting a bedroom inside the day care.

The pair initially faced local murder charges, but the U.S. Attorney's Office for the Southern District of New York also lodged federal drug charges against them.

On Monday, federal prosecutors also announced charges against a third person, Renny Antonio Parra Paredes, who is charged with conspiracy to distribute narcotics resulting in death. Prosecutors accused Paredes of having an "instrumental role" in the group's alleged drug distribution operation.

Medical teams had to use Narcan, the nasal spray that can reverse opioid overdose, on all four children. The New York Police Department says tests confirmed fentanyl, an intensely strong synthetic opioid that can be deadly in tiny doses, was present in the three surviving victims.

Fentanyl cake was found on top of kids' playmats

Details of the case are disturbing, including the tragic death of 1-year-old Nicholas Dominici and the hospitalization of three other young children, including an 8-month-old girl. A federal complaint was unsealed on Sept. 19, alleging that a kilogram block of fentanyl was kept in the same space the kids occupied.

"There, despite the daily presence of children, including infants, the defendants maintained large quantities of fentanyl, including a kilogram of fentanyl stored on top of children's playmats," according to an affidavit signed by Drug Enforcement Administration Special Agent Kyle Harrell.

Brito's room, which he rented for $200 a week, also held equipment suggesting a large drug operation: a "kilo press," authorities say, adding that the equipment is used to recompress drugs in powder form. Two other presses were found elsewhere in the day care.

The presses are "commonly used by narcotics traffickers at 'mills' or other locations where narcotic drugs are broken down, combined with fillers or other narcotics, and portioned for sale," the affidavit states.

Children were struck ill Friday afternoon

Mendez called 911 around 2:40 p.m. on Sept. 15, reporting that three children at her day care were unresponsive. An ambulance then took the three children — ranging from 8 months to 2 years old — from the day care to a nearby hospital.

"Quick-thinking FDNY EMS personnel administered Narcan to these three children and removed them to Montefiore Hospital," NYPD Chief of Detectives Joseph Kenny said of the case.

A fourth child, age 2, whose mother had picked up from the day care earlier in the day was also brought in for care, and the staff at Bronx Lebanon Hospital administered Narcan, after seeing symptoms of opioid exposure.

But it was too late for Dominici, who was pronounced dead at the hospital.

"Nothing will give me back our son. Not all the gold in the world will make up for his life," the boy's father, Otoniel Feliz, told New York's PIX11 News. "For a parent, the life of a child is priceless and the value will always be in my heart."

Mendez and Brito face numerous charges

The Bronx district attorney's office charged Mendez and Brito with murder and attempted murder, as well as depraved indifference.

Mendez's attorney, Andres Aranda, has said he doesn't believe his client knew what Brito was doing in the room she rented.

But the federal affidavit alleges that Mendez lied to investigators when she claimed no one had been to the day care around the time of the apparent overdoses.

Citing phone records, the affidavit says Mendez made three calls immediately before she dialed 911 — one to an employee at the day care and the others to her husband. She called her husband again after contacting 911.

"Several minutes before emergency personal arrived at the scene, surveillance footage showed [Mendez's husband] enter the Daycare empty-handed and then exit approximately two minutes later carrying what appears to be two shopping bags weighted with contents," the federal document states. Instead of leaving by the front door, it adds, he exited the building through a back alley.

Because of the circumstances and other phone evidence, Harrell said, the actions were consistent with someone attempting to hide evidence.

Harrell also says that an inspection of Mendez's phone showed that she "deleted approximately 21,526 messages from an encrypted messaging application" dating from March of 2021 to Sept. 15 — the day the children were sickened.

Both Mendez and Brito denied knowing anything about any drugs in the day care, according to Harrell's affidavit. It notes that Brito's phone held messages that, according to the DEA agent, "indicate his participation in narcotics trafficking."

In a separate complaint, Harrell said Brito had earlier exchanged "numerous" encrypted messages with Paredes, who used the nickname "El Gallo." Harrell said the messages show both of their involvement in trafficking narcotics.

Police searching an apartment where Paredes had been staying found tools for drug distribution, Harrell said, including a digital scale and empty glassine envelopes stamped with the words "Red Dawn."

The day care had recently been inspected

The Divino Niño Daycare was appropriately licensed and registered, with a listed capacity of eight children, from 6 weeks to 12 years old, according to city records.

The day care, which comprises a one-bedroom apartment on Morris Avenue with a bedroom, a playroom, a bathroom, and a kitchen, had been inspected in early September; records describe the visit as an unannounced annual inspection.

Prosecutors in the Bronx say the addition of federal drug charges won't alter their plans to pursue a murder case against Mendez and Brito.

"Our case is proceeding," Patrice O'Shaughnessy, communications director at the Bronx District Attorney's office, told NPR, adding that the next step is for the case to be considered by a grand jury. The jurors, she added, are due back in court later this week.

Copyright 2023 NPR. To see more, visit https://www.npr.org.