The “main player” in the Bronx drug mill that posed as a day care center — and eventually led to a toddler’s death from fentanyl poisoning — has taken a plea deal that will likely put him behind bars for decades, federal prosecutors announced Monday.

Felix Herrera Garcia was initially hit with a federal charge of conspiracy to distribute narcotics resulting in death after four kids under the age of 3 were poisoned by the drugs he and his compatriots were dealing at Divino Niño Daycare in Kingsbridge.

One of the kids — 1-year-old Nicholas Feliz Dominici — died last September due to what the city medical examiner’s office ruled a homicide by acute fentanyl intoxication.

Just before jury selection was set to begin Monday in Garcia’s trial, he chose to admit to three charges in connection with the death: conspiracy to distribute narcotics resulting in death and serious bodily injury, possession with intent to distribute narcotics resulting in death and possession with intent to distribute narcotics resulting in serious bodily injury. 

Taken together, they threaten to imprison Garcia — who has been described as “the main player” in the alleged drug business — for 20 years to life, Manhattan federal prosecutors said.

Authorities have said Garcia — along with wife and co-defendant Grei Mendez and another man, Carlisto Brito of the Bronx — ran a fentanyl mill out of the basement of a building they also used as a day care.

This led to four children — including the now-deceased Nicholas — being sickened after they were exposed to the deadly synthetic opioid, which is about 50 to 100 times stronger than heroin.

The wannabe drug kingpins allegedly stored the fentanyl under two trap doors inside the day care center and in closets on top of play mats.

“This was not really a day care center — this was a drug operation,” Bronx District Attorney Darcel Clark said right after their arrest. “And they used babies as a shield. I’m outraged.”

The three other children — an 8-month-old girl, her 2-year-old brother and another 2-year-old boy — had to be revived using naloxone, the overdose reversal drug commonly known by the brand name Narcan.

Authorities arrested Mendez and Brito — who is Herrera’s cousin — the day after Nicholas’ death and charged them with murder, assault and child endangerment.

Herrera was later nabbed on a bus by Mexican authorities after more than a week on the run.

The local case is still pending. The next court date is set for July 30.

Aside from the local charges, the three faced federal charges related to the boy’s death. The other two cases are still pending as well.

A fourth defendant, 38-year-old Renny Antonio Parra Paredes of the Bronx, was also charged by Manhattan federal prosecutors for his role in the alleged drug operation. 

Two weeks ago, he pleaded guilty to conspiring to distribute narcotics — and stipulated that his conduct caused death and serious bodily injury, the feds said.

He also faces 20 years to life in prison

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

Authorities initially said they uncovered a kilo of fentanyl sitting on mats the children slept on, according to court papers. They also seized several “kilo presses,” which are normally used to combine the drug with cocaine or heroin.

A week later, more drugs were found hidden under a trap door at the day care center, including 6 kilos of fentanyl, heroin and other controlled substances, authorities said.

The stash was discovered in a 4-inch-deep hiding spot below the apartment’s tile-on-wood flooring, according to photos shared by the department.

All in all, the drug mill had more than 10 kilos of narcotics hidden in the space, the feds said.