A day after a month-old baby boy stopped breathing at a Newark office of New Jersey's child welfare agency, investigators said yesterday that they had ruled out foul play, but were no closer to determining what had caused his death.
The Newark police said the preliminary findings of an autopsy on the baby, Zaire Knott, showed no signs of physical trauma, leading detectives to eliminate homicide as a possible cause.
The state's child advocate, Kevin M. Ryan, said the autopsy also showed that Zaire's death was not caused by an adverse reaction to a pair of vaccines that he received hours before.
A final autopsy report has not been prepared, and officials said that the exact cause of death might not be known until the completion of additional tests, including those to determine the presence of toxic substances.
"There was nothing physical, like blunt force trauma, that caused the child to die," said Charlotte L. Smith, a spokeswoman for the Essex County prosecutor's office. "We won't know what happened until we see the report."
One theory that emerged in the official police report of the death is that the baby somehow choked.
According to the report, the emergency room physician who pronounced Zaire dead at St. Michael's Medical Center in Newark said he "believed that the baby most likely choked, possibly on his own formula."
The report also said a child welfare worker who had helped try to revive Zaire noticed that a bloody discharge dripping from his nose looked as if "it was mixed with milk."
Because Zaire's death was not ruled a homicide, the Newark police said that they had closed their investigation. A review of the case by Mr. Ryan's office, however, was continuing. Mr. Ryan said his early findings had also ruled out abuse or neglect as a cause of death. "At this point, I'm unaware of any evidence of foul play," he said.
Zaire's death occurred at a tense moment for New Jersey's child welfare agency, the Division of Youth and Family Services. The agency was criticized in a recent independent report for not making enough progress in putting court-ordered changes in place.
A child welfare reform advocacy group, Children's Rights Inc., said in court papers last week that children in the state's care were in immediate danger and asked a federal judge to intervene in the overhaul of the system, a step that could lead to the placement of the agency in receivership.
Acting Gov. Richard J. Codey has promised changes to the agency, including the appointment of a special child welfare adviser. Mediation discussions, intended to avert a takeover of the system, are scheduled to begin on Monday.
It was against the backdrop of an ailing agency struggling to heal itself that Zaire died Thursday afternoon. State officials said that the infant, who had been in foster care since birth, had been taken to a clinic at 465 Mount Prospect Avenue in Newark for immunizations that morning.
After returning to his foster mother's home, Zaire was to visit with his biological mother on the third floor of the child welfare agency's offices at 153 Halsey Street in Newark.
When a worker picked up Zaire at his foster home in Newark, officials said, the child was either coughing or experiencing some other mild discomfort that led the worker briefly to consider canceling the visit.
Once the foster mother assured him that Zaire was fine, the worker took the infant to the office where, around noon, he noticed that the infant was not breathing. According to the report prepared by the Newark police, the worker, who was not identified, took Zaire, still strapped in his car seat, to a nurse in the Halsey Street building.
The nurse, according to the report, immediately noticed that Zaire's lips were blue. The report also indicates that even though the nurse tried to resuscitate Zaire, she did not notice his chest or abdomen moving to indicate that air was getting into his body.
Paramedics were called and Zaire was pronounced dead at the hospital at 12:46 p.m.
Child welfare officials first believed that Zaire might have had a bad reaction to two vaccines that he received that morning for hepatitis B and polio. But Mr. Ryan said the autopsy had shown that that was not the case.
"There is no medical evidence whatsoever to support the assertion that Zaire died as a result of the immunizations," Mr. Ryan said, and encouraged parents to continue vaccinating their children.
Medical experts said that it was exceedingly rare for children to die from reactions to vaccines. Dr. Paul A. Offit, chief of the section of infectious diseases at Children's Hospital of Philadelphia, said allergic reactions could stem from causes like egg proteins, which are in some vaccines, but not in the hepatitis B vaccine. He said the polio vaccine, which is made of raw killed virus, did not cause allergic reactions either.