Two of the three suspects arrested in the death of a 1-year-old boy from fentanyl exposure at a Bronx, New York, day care center in September, and the sickening of three other children from the drug, which was stashed at the business, pleaded not guilty Thursday to murder charges.

Defendants Grei Mendez, the operator of the day care center, and Carlisto Acevedo Brito entered their pleas in a Bronx courtroom, in answer to the charges stemming from a case prosecutors said "shocked the conscience" of New York City.

The pair entered their pleas after they were both indicted Thursday along with Mendez's husband, Felix Herrera Garcia, on charges of murder with depraved indifference to human life in connection with the death of 22-month-old Nicholas Dominici, whom the New York City Office of the Chief Medical Examiner determined died of fentanyl exposure at the Bronx day care center, which prosecutors said was a front for drug trafficking.

"This is a catastrophe. Our sorrow is matched only by the outrage because these babies were used as shields to protect a narcotics operation,” Bronx District Attorney Darcel Clark declared at a news conference Thursday, which was attended by the families of the children who were exposed to fentanyl at the day care center.

Grei Mendez, 36, Felix Garcia, 34, and Brito, 41, a cousin of Garcia and a tenant of Mendez's, have all been charged with second-degree murder, criminal possession of a controlled substance, manslaughter, assault, and child endangerment. Garcia is expected to be arraigned later Thursday.

During Thursday’s court hearing, Nicholas Dominici's mother sat in the courtroom gallery, wailing.

“I understand that justice will be done,” Nicholas’ father, Otoniel Feliz, told reporters Thursday. "It will not bring my son back."

Feliz’s hand shook as he displayed a photograph of his son, and his voice broke with emotion.

"We trusted this day care because everything was going OK," Feliz said. "Every single day, the lady in charge sent text messages to my wife. We trusted her because she kept us updated. We never imagined this was going to happen."

"This case is the bleakest reminder that we must be relentless in removing drug traffickers from our community," Clark said, adding that her office would be taking aim at daycare centers run out of private homes. "We will get justice for them. But what we have to do is make sure this never, ever happens again to any other child."

Garcia, who allegedly fled the day care center on the day Nicholas died and was arrested in Mexico after a weeklong manhunt, is also in custody on state murder charges in the case.

All three defendants are also charged in a separate federal case with narcotics possession with intent to distribute resulting in death, and conspiracy to distribute narcotics resulting in death.

Felix Garcia appeared in federal court on Wednesday and was detained on consent. He was not arraigned in federal court and has not entered a plea in either the state or federal cases.

A fourth defendant, Renny Antonio Parra Paredes, was also arrested in the fentanyl exposure incident and is facing federal charges of conspiracy to distribute narcotics.

All four suspects are scheduled to appear in federal court on Oct. 12.

The suspects are accused of storing a kilo of fentanyl in a closet at the day care center, prosecutors said. Six kilos of fentanyl-laced heroin and other controlled substances were found beneath a trap door at the center that was hidden by a padded mat that the children used to nap on, prosecutors said.

Mendez called 911 on Sept. 15, reporting that the children had fallen ill, according to police. Investigators said that before Mendez called 911, she phoned her husband.

In all, four children were sickened from fentanyl exposure at the day care center, and paramedics used Narcan to revive three of them. Nicholas could not be resuscitated and died at a hospital. The children who survived ranged in age from 8 months to 2 years, officials said.

Mendez is also accused of deleting more than 20,000 text messages that she and her husband exchanged between March 2021 and the day Nicholas Dominici died from fentanyl exposure, authorities said.

Garcia was captured on surveillance video allegedly fleeing the day care via a back alley and carrying two heavy shopping bags while the children were ill, according to prosecutors.

Grei Mendez's attorney claimed she was not aware the drugs were stashed at the center. Attorneys for the other suspects have not publicly commented on the charges.