Felix Herrera Garcia, the husband of the owner of the Bronx day care where a 1-year-old died of suspected fentanyl poisoning, returned Thursday to the United States and was placed under arrest after he was initially taken into custody in Mexico earlier this week.

Herrera Garcia is due to make an initial appearance in federal court in San Diego later Thursday before he is brought to New York where he faces federal charges, along with three others, including his wife, in connection with the death of Nicholas Dominici and the poisonings of three other children at Divino Nino day care.

The death of Dominici highlighted how New York City is awash in fentanyl, which is now the most common drug involved in overdose deaths in the city. In response, Mayor Eric Adams said Thursday he would convene a fentanyl summit next week.

"As opioid use skyrockets, illegal drugs are often contaminated with fentanyl or other dangerous substances, and overdoses have hit historic levels, including in New York City," Adams said. "We cannot allow this crisis to continue taking lives and destroying communities."

Herrera Garcia was seen on surveillance video carrying shopping bags and running from the day care out a back alleyway before first responders arrived to tend to the ailing children, according to prosecutors.

His wife, Grei Mendez, pulled their 2-year-old son from her own day care last year after she worried he was exhibiting signs of fentanyl exposure, law enforcement sources familiar with the case told ABC News. Mendez never reported the suspected exposure to police and did not allow the boy to return to the facility, according to the sources. However, she kept the day care open for other children.

NYPD officers and agents from the Drug Enforcement Administration tracked him to Texas on Sunday, but learned Monday he had managed to slip across the southern border into Rosalia, Mexico. Working with Mexican authorities, the DEA and other federal agents isolated him Tuesday on a bus headed to Sinaloa.

"Felix Herrera was arrested for his alleged role in running a fentanyl mill hidden inside a Bronx daycare, which caused the tragic death of a one-year-old boy and seriously injured three other children," U.S. Attorney Damian Williams said in a statement. "Herrera's arrest on the other side of the nation reflects our tireless pursuit of Herrera, who fled the daycare even as the children he abandoned inside were suffering from his poisonous trade."

Herrera Garcia did not go through extradition. Rather, he was expelled by Mexico and walked across the border into California where he was detained by Customs and Border Protection, law enforcement sources familiar with the case told ABC News.

He is charged with conspiracy to distribute narcotics resulting in death in connection with the poisoning of four children under the age of 3. He faces up to life in prison.

Herrera Garcia has been known to law enforcement since last October, when he called 911 to report a 42-year-old man, believed to be his brother, unconscious on a bedroom floor with pills, according to sources. The man later died of an apparent overdose.