Two people have pleaded guilty to federal drug charges stemming from the fentanyl poisoning death of a 1-year-old baby and the hospitalization of three other children under the age of 3 at a Bronx day care, where they ran a fentanyl operation, officials said.

In September, four children were hospitalized of suspected opioid exposure that occurred at the Divino Niño day care center. One-year-old Nicholas Dominici died at a hospital, and three other children survived after treatment.

Four adults were charged with federal crimes in relation to the illegal drug operation running out of the day care. Felix Herrera Garcia, husband of day care owner Grei Mendez, pleaded guilty on Monday to conspiracy to distribute narcotics, resulting in death and serious bodily injury, and possession of narcotics with intent to distribute, resulting in death and serious bodily injury. The plea came the morning trial was set to begin, according to the U.S. Attorney's Office for the Southern District of New York.

A man charged as a co-conspirator, Renny “El Gallo" Parra Paredes, also pleaded guilty in late May to conspiring to distribute narcotics and stipulated that his conduct caused death and serious bodily injury, according to a news release. They both face up to life in prison for each count.

"We said at the time that this case shocks the conscience of the city, and now Herrera Garcia and Parra Paredes have been brought to justice for this heinous crime," U.S. Attorney Damian Williams said in a statement.

What happened at the Bronx day care?

On Sept. 15, 2023, police responded to a report of unconscious children at a day care center in the Bronx. Three children were unresponsive and hospitalized. The 1-year-old boy died, while an 8-month-old girl and her 2-year-old brother were able to be saved. Another child who had been sent home before police arrived also survived after being treated at a hospital.

"This happened because, as they admitted in court, Felix Herrera Garcia and Renny Antonio Parra Paredes operated an illegal fentanyl operation out of the center, where they processed the deadly drugs for sale," Williams said.

During an investigation, police found secret compartments under the floors of the day care where more than 10 kilograms of narcotics were being stored. Police also said in court filings they found a kilogram of fentanyl stored on top of children's playmats.

The case prompted increased scrutiny of New York City day care centers and a backlog of background checks for the adults who work at them.

Suspects tried to cover up drug operation

The drug operation had been going on since about October 2022, prosecutors said.

Mendez, the operator of the center, and Carlisto Acevedo Brito, her cousin-in-law who rented a room there, also face charges. Prosecutors said in filings that Mendez and Brito attempted to cover up the drug operation while the children suffered from the effects of the fentanyl exposure.

Mendez allegedly called Herrera Garcia and Parra Paredes before she called 911 when she discovered the children had been exposed, according to a criminal complaint.

Herrera Garcia was also seen on surveillance cameras smuggling shopping bags out a back alley before police arrived on the scene.

Authorities searched for Herrera Garcia for weeks before he was arrested on a bus in Sinaloa by Mexican authorities and Drug Enforcement Administration agents, according to news reports at the time.

"Herrera Garcia has now been held accountable in the tragic loss of little Nicholas, the serious injury of Abel, and the harm to Kiara and Jaziel," Bronx County District Attorney Darcel D. Clark said in a statement.

Attorneys for Herrera Garcia and Mendez declined to comment on the case.

Parra Paredes has "accepted responsibility for his conduct," his lawyer, John Kaley, told USA TODAY.

"He feels terribly sorry that children were hurt, and he offers his sincerest apology to the families affected by the drugs at the daycare center," Kaley said. "It’s a tragic circumstance."

An attorney for Acevedo Brito did not immediately respond to a request for comment from USA TODAY.

Contributing: Cybele Mayes-Osterman, USA TODAY