A Manchester, N.H., woman was arrested Saturday and charged with second-degree murder in the death of her 21-month-old daughter.
The arrest of Katlin Paquette, 22, followed a three-week investigation by authorities, according to the New Hampshire Attorney General's Office.
Emergency personnel were called to 437 Belmont St. in Manchester around 1:30 p.m. on Sept. 5 to treat Sadence "Sadie" Willott, Paquette's daughter, Senior Assistant Attorney General Benjamin Agati said Saturday.
The girl died the next day at Dartmouth-Hitchcock Medical Center in Lebanon, N.H. An autopsy conducted on Sept. 8 determined the death to be a homicide caused by blunt impact head injuries, according to a statement from the attorney general's office.
Paquette was charged with murder "manifesting extreme indifference to the value of human life," the statement said, and was accused of "recklessly [causing] Sadence Willott's death through an application of physical force causing Sadence to suffer a fatal brain injury."
Agati declined to say whether a weapon was used or whether others lived at the same residence as Paquette and her daughter. Investigators interviewed doctors and witnesses, Agati said, and a judge granted a warrant for Paquette's arrest.
Paquette is to be arraigned Monday. Agati said bail has not been set, and an attorney would be appointed for Paquette if she did not already have one.
Jack Newsham can be reached at jack.newsham@globe.com.