Boulder County District Attorney Michael Dougherty will not file criminal charges against the officer who fatally shot Ashlyn Brownell, 31, following a standoff with police outside a Longmont home earlier this year. Dougherty determined the shooting was legally justified under Colorado’s use-of-force laws, according to a decision letter released this week. The incident began March 19 at 4 p.m., when Longmont police received a 911 call from Brown…