A 25-year-old northern New York woman charged in the death of her 6-month-old niece has admitted to choking the baby after the infant became fussy, authorities said.

State police told local media outlets Thursday that Amber Simpson told investigators that she grew frustrated with Rachel Wood-Main's fussing before choking the infant in the apartment Simpson shared with her boyfriend in the Jefferson County village of Carthage.

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The child was choked early Tuesday morning but authorities weren't called until 15 hours later when Simpson's boyfriend noticed the infant was unresponsive, police said. Authorities say the baby was pronounced dead at a hospital late Tuesday night.

Simpson was arrested Wednesday night and charged with manslaughter. She's being held in jail on $30,000 bail. Information her lawyer wasn't immediately available.

Simpson had custody of the baby, police said.