PITTSBURGH — A local officer was justified in shooting a 68-year-old northwestern Pennsylvania woman who swung a knife at him at her home in July, state police and the district attorney announced Tuesday.

In a report, troopers from the Franklin barracks detailed the encounter in which Marilyn Elizabeth Peterson was killed by an unnamed officer in Oil City.

The state police said Venango County District Attorney Marie Veon reviewed their findings and determined the officer shouldn’t be prosecuted and used “justifiable force to prevent serious bodily injury or death to himself or others.”

The shooting happened about 9 p.m. July 16 after police were called to the residence where Peterson was allegedly acting irrationally and threatening other family members, including children, the report said.

State police determined Peterson was threatening to kill herself and the officers with a large kitchen knife when they arrived.