Kimberly Aponte, 19, hid the unwanted pregnancy from her family, authorities said.
Aponte gave birth before dawn Saturday to a full-term boy whom she then wrapped in a towel and stuffed into a hamper, they said.
Aponte's father called city police to the family's Hackensack Avenue apartment Saturday afternoon, Bergen County Prosecutor Mark Musella said.
There, the officers found the lifeless child, he said.
Aponte, who was in her bedroom, was taken by ambulance to Hackensack University Medical Center, the prosecutor said.
His Major Crimes Unit investigated and charged her with first-degree manslaughter, Musella said.
Aponte remained hospitalized in police custody until Tuesday, when she was taken to the county lockup.
Amid concerns over her mental health, Central Judicial Processing Court judge in Hackensack released Aponte Tuesday afternoon -- with conditions -- pending the outcome of the case.
Manslaughter in New Jersey (N.J.S.A. 2C:11-4) is charged when prosecutors believe that someone "consciously disregarded a substantial and unjustifiable risk while causing another person’s death."
Aggravated manslaughter is the most serious manslaughter charge, referring to a person who "causes a death while manifesting extreme indifference to human life."
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