Angelica Huertas, 24, had been facing endangering the welfare of a child charges after she allegedly left her 11-month-old son in the bathtub, unsupervised, with his 3-year-old sister.
When she returned, Elijah Pardella was submerged and unconscious.
He was rushed to Brookdale Hospital, where he was pronounced dead.
Prosecutors on Tuesday decided the facts of the case did not rise to endangering the welfare of a child.
Huertas was released from custody Tuesday afternoon.
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