A 15-year-old girl was justified in shooting her mother’s boyfriend as he threatened, attacked and strangled her earlier this month, prosecutors said this week.

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Steven Kelley, 46, was yelling that he would cut Chandra Nierman's throat and kill everyone else in the house, which included her 12-year-old son, and 15- and 16-year-old daughters on Aug. 8, Rutherford County Sheriff's Office said.

Kelley, a convicted felon who frequently carried a firearm, kept other guns in the house, investigators said. Nierman’s son got one and gave it to his 15-year-old sister, who shot Kelley twice in the chest as he was assaulting their mother, investigators said.

Nierman’s 16-year-old daughter was taken to a hospital after one of the rounds fragmented and hit her in the leg, investigators said.

Nierman was treated for serious cuts and bruises, officials said.

Kelley, who had two active domestic violence protection orders in place by women in Ohio and Indiana, had previously threatened Nierman on Aug. 4 when he assaulted her and fired a gun inside the house, deputies said.