A prosecutor has declined to file criminal charges against a Missouri police officer who shot and killed a woman and her infant child last year.

Independence police officers had responded to a reported assault in November at an apartment building. They were figuring out how to arrest the woman, who was nonverbal and communicating with nods and gestures, when she abruptly grabbed a butcher knife from a bedside table and moved toward the officers while holding the child, Jackson County Prosecutor Melesa Johnson’s office said Friday.

One officer backed away, but the other was against a closet and couldn’t escape, Johnson’s office said. He fired four shots as the woman moved toward him with the knife, the office said. The shots struck and killed the woman and her child, identified by KCUR news as 34-year-old Maria Pike and her 3-month-old daughter, Destinii.

Johnson’s office said the officer’s use of deadly force “falls within the protection of the law.”

Her office also noted there wasn’t enough evidence to conclusively prove the officer intentionally shot the infant.