NORRISTOWN (AP) — Authorities won't file charges against a Pennsylvania state trooper who shot and killed his pregnant wife at their suburban Philadelphia home.



A three-month investigation found that Joseph Miller's gun went off as he tried to clean it at home in East Norriton.



The bullet struck his wife in the head. Both 34-year-old Joanna Miller and her 22-week-old unborn baby died.



The Montgomery County district attorney's office concluded the March 7 shooting was negligent but accidental.



Authorities said in a news release Friday that all evidence indicated the Millers were "a close-knit, loving family excited about the pending arrival of a new baby." They had four other children.