Updated

The mother of a newborn girl whose body was found in a New Jersey park on Christmas Eve nearly 40 years ago has been identified and is now charged in the death, authorities announced Thursday.

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The infant, dubbed "Baby Mary" by a police chaplain, was found by two young boys in a secluded park in Mendham Township in 1984, Morris County Prosecutor Robert Carrol said. The child's umbilical cord was still attached when she was found, and she was wrapped inside a towel inside of a plastic bag. She was alive when she was abandoned, Carrol said.

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The mother of a newborn baby found dead in a New Jersey park nearly 40 years ago has been charged with manslaughter.

The woman, who was 17 at the time, was arrested in South Carolina on April 24 and charged as a juvenile with manslaughter. She is not in custody but is "being monitored," Carroll said.

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The woman's name was not released since she was a juvenile when the death occurred. The identity of the child’s father — who was 19 at the time — was also determined, Carroll said, but authorities said he was unaware the baby had been born and he was not involved in her death. He died in 2009.

A possible motive or reason for abandoning the baby has not been disclosed.

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A breakthrough in the case came several years ago when a DNA match between the infant and the father was made, Carroll said, though he declined further comment.