Police and Illinois' child welfare agency have said staff at a Chicago-area hospital did not alert them after determining that a bloodied woman who arrived with a gravely-ill newborn had not just given birth to the baby boy, as she claimed.
The woman, Clarisa Figueroa, was charged more than three weeks later with killing the baby's mother, Marlen Ochoa-Lopez, after police found her body outside Ms Figueoa's home.
Chicago police said she cut Ochoa-Lopez's baby out of her womb on 23 April, then called 911 to report she had given birth to a baby who was not breathing.
Paramedics took Ms Figueroa and the baby to Advocate Christ Medical Centre in suburban Oak Lawn.
Ochoa-Lopez's family spent those weeks searching for her and holding press conferences pleading for help finding her, unaware that the child was in a neonatal intensive care unit on life support.
The baby remained hospitalised on life support on Saturday, according to authorities.
Prosecutors said when Ms Figueroa was brought with the baby to the hospital, she had blood on her upper body and her face, which a hospital employee cleaned off. They also said Ms Figueroa was examined at the hospital and showed no physical signs of childbirth.
Advocate Christ Medical Centre has declined to say whether or when it contacted authorities, citing state and federal regulations.
Oak Lawn police said they were not contacted about Ms Figueroa by the medical centre or any other agency.
Illinois Department of Children and Family Services spokesperson Jassen Strokosch said on Saturday the agency was alerted 9 May that there were questions about who had custody of the child in order to make medical decisions. He said he could not speculate about why the agency was not contacted sooner.
"We don't know what was happening at the hospital," he said.
Mr Strokosch said the Department of Children and Family Services was alerted by someone required by law to contact the department about suspected abuse or neglect, but he could not say who contacted the agency.
However, that was after Chicago police had connected Ms Figueroa to Ochoa-Lopez's disappearance.
Chicago Police Superintendent Eddie Johnson said police learned Ochoa-Lopez was missing when her husband reported it on 24 April.
On 7 May, Chicago police learned from one of Ochoa-Lopez's friends that she had been communicating via a private Facebook group with Ms Figueroa about buying clothing. Police then went to Ms Figueroa's home, where her 24-year-old daughter eventually told them her mother had recently had a baby.
"There was nothing to point us in that direction in the beginning," Mr Johnson told reporters on Thursday, after police had arrested Ms Figueroa and her daughter on murder charges.
Police spokesperson Anthony Guglielmi said on Saturday that authorities had to subpoena medical records from the hospital for Ms Figueroa and the child.
He said police did not learn Ms Figueroa showed no signs of childbirth until "a couple weeks" after she was examined.
Both Mr Johnson and Mr Guglielmi referred questions about hospital protocol and policies to the medical centre. A spokesperson said in an emailed statement: "We have been cooperating with authorities and as this is an ongoing police matter, we're referring all inquiries to local law enforcement."
DNA testing determined Ms Figueroa was not the baby's mother and that Ochoa-Lopez's husband was his father.
Mr Strokosch said his department let protective custody of the child lapse on 13 May because his father had been identified.