Two days after Christmas, Darwin Santana-Gonzalez, a curly-haired 1-year-old, was toddling around a Bronx apartment where, the police said, a potent mixture of heroin and fentanyl was being prepared, stamped and packed for sale.
The powerful opioids had been placed in packages, the authorities said, along with a related drug, acetylfentanyl, creating the sort of deadly cocktail that has led to a surge of overdose deaths in the Bronx and beyond. Somehow, some of the mix also ended up in Darwin.
By 10 a.m. that morning, the police said, the little boy had stopped breathing and was dead.
Darwin’s parents, who had flagged down police as they attempted to rush him to the hospital, were charged in January with multiple counts of drug possession, but his father fled the country. On Wednesday, the police announced that his mother, Daira Santana-Gonzalez, who was in custody, had been charged with murder in her son’s death.
Fentanyl variants can be 50 times stronger than heroin and have appeared in New York mixed into a number of drugs, including those sold as pure heroin, cocaine and prescription pills.
“The amount of fentanyl it would take to kill you or me would fit on the tip of your baby finger, and a small child would be much more susceptible,” said Bridget Brennan, the city’s special narcotics prosecutor.
Just two days before Darwin died, two parents in Michigan were charged with murder in the death of their 18-month-old daughter, Ava Floyd, who had ingested fentanyl. The authorities discovered evidence of drug manufacturing and distribution inside their home, news reports said.
In all, the opioid crisis in the United States claimed the lives of almost 9,000 children from 1999 to 2016, researchers from Yale University reported in a study in December. While most of the deaths were ruled accidental, some were ruled homicides. About 7 percent of the children who died from overdoses, the researchers found, were younger than 5 years old.
Ms. Santana-Gonzalez’s lawyer did not respond to a request for comment.
In March, Ms. Santana-Gonzalez told The Daily News in a tearful interview on Rikers Island that she was not aware of any drug activity in her home. She said her husband had been abusive, and that he had fled shortly after Darwin’s death.
“Everyone knows I loved Darwin,” she said. “I would never do anything to hurt my son. l loved my son.”
Frances Gomez, 25, who lives in the building, said he was smoking in the lobby on the morning of Dec. 27 when he saw Darwin’s father, Modesto Antonio Gonzalez, rush outside with his son’s lifeless body in his arms.
“The father was crying and saying, ‘I can’t believe it. My baby, my baby, oh my God,’” Mr. Gomez said in an interview on Wednesday. Mr. Gomez said he had held Darwin in his arms briefly while his parents scrambled from the apartment to a car. The image of the infant, blue and foaming at the mouth, haunted him for weeks.
In recent years, the Bronx has become the center of New York’s opioid crisis.
In 2017, the Bronx overtook Staten Island as the borough with the most fatal drug overdoses, with 363 of the city’s record 1,487 fatal overdoses. About 60 percent of victims were Hispanic, mirroring the overall demographics of the borough, according to a Columbia University study of the opioid crisis in the Bronx.
Prompted by the overall increase in city drug deaths, in 2017 Mayor Bill de Blasio launched HealingNYC, a plan to spend $60 million to combat the problem. Outreach workers have widely distributed naloxone, the overdose antidote; the city has also printed posters that warn New Yorkers about the dangers of fentanyl.
But while these efforts have helped tamp down the number of fatal overdoses in most parts of the city, deaths have continued to climb in the Bronx. In 2017, the overdose death rate per capita in the South Bronx was higher than any place in the nation other than West Virginia, according to city health officials.
Fentanyl typically arrives in the United States by mail from China, and is smuggled into the Bronx by mules working for Mexican cartels, according to the Office of the Special Narcotics Prosecutor for New York, which seized more than 500 pounds of fentanyl in the city in 2018. The vast majority of it was found in the Bronx.
The drugs are prepared and packaged not only for Bronx users but for distribution throughout the city and region. Distributors include large-scale traffickers but also small, household operations.
Darwin, the police said, lived with his parents in the Morris Heights section of the Bronx, in an apartment that the police said appeared to house that sort of operation.
Roberto Guillen, the building’s superintendent, said in an interview on Wednesday that he had been in the apartment a week before Darwin’s death to make a repair in the kitchen and did not see evidence of drugs.
“Everything was normal there,” he said. “I feel bad because she was a nice lady.”
Two other people, Jose Furman Gonzalez and Chayenne Mendez Rodriguez, suspected with helping to prepare drugs in the apartment, were also charged with drug possession. They are believed to have fled to the Dominican Republic, along with Mr. Gonzalez, investigators said.
Laura Dimon and Ashley Southall contributed reporting. Sheelagh McNeill contributed research.