Unholy (2007)

Martha, a widow living in rural Pennsylvania, comes home to find her daughter about to blow her own head off with a shotgun in the basement of their house. Martha doesn't succeed in stopping her child's horrific demise, but the girl's death gradually leads the grieving mother to investigate a conspiracy that involves a legendary local witch, Nazi dabbling with the occult, and secret government experiments, with the story even referencing the fabled Philadelphia Experiment