New York City police are hunting for the husband of a nursery owner after a one-year-old died from a suspected drug overdose at the facility and three other children were taken to hospital.
Nicholas Dominici died after inhaling fentanyl at the nursery operated by Grei Mendez, who has been arrested.
Fentanyl was found under a mat used by the children for napping, police said.
The synthetic painkiller, 50 times more powerful than heroin, has been blamed for a rise in US drug deaths.
On Wednesday, an NYPD spokesperson told the BBC that police were still trying to ascertain the identity of the woman’s spouse, whom charging documents describe as a co-conspirator.
Video footage shows the husband fleeing before police arrived.
There is no reward currently being offered for his arrest.
Three children were revived with Narcan, an overdose-reversing drug, after police were called to the Divino Niño nursery in the Bronx on Friday night.
One kilo of fentanyl was discovered “underneath a mat where the children had been sleeping earlier”, said NYPD chief detective Joseph Kenny on Monday.
The owner of the Divino Niño nursery, Ms Mendez, 36, and her tenant, Carlisto Acevedo Brito, 41, are facing federal charges of narcotics possession “with intent to distribute resulting in death”, according to federal prosecutors.
Surveillance footage and phone records show that Ms Mendez called her husband several times after finding the children ill – before she even contacted 911. Her husband then arrived and removed several full shopping bags from the nursery, officials said.
Ms Mendez also allegedly deleted approximately 20,000 texts from her phone before her arrest, according to prosecutors. Authorities were later able to recover the messages.
A lawyer for Ms Mendez said his client denies the charges and was unaware that drugs were being kept in the nursery.
Police say the fentanyl recovered at the scene could have killed 500,000 people.
City health inspectors conducted a surprise visit of the nursery on 6 September, but did not identify any violations.
Mayor Eric Adams defended the inspectors on Wednesday, telling TV network NY1: “That inspector did their job. And we should not in any way give an impression that inspector failed those children and their families.”
“Who did not do their job?” he added. “Those individuals who were supposed to protect the children there.”
The father of a two-year old boy that survived the fentanyl exposure told ABC News that there were warning signs about the nursery.
The man told the network that, looking back, he considers it suspicious there were three men standing outside the building on Thursday and Friday.
Virtually every corner of the US, from Hawaii to Alaska to Rhode Island, has been touched by fentanyl, new research shows.
The death toll from fentanyl includes a growing number of very young children.
Over the weekend in Washington state, one child died and two others got sick in separate incidents involving fentanyl, police say.
Across the country, prosecutors are bringing charges against parents whose children died after consuming the deadly drug.
