A federal judge on Friday denied a government request for an additional mental health evaluation for a man accused of firing shots at the White House. The judge, Magistrate Judge John M. Facciola, said prosecutors could request such an evaluation in the future, if it becomes necessary. But the judge said there was no evidence to suggest that the suspect, Oscar Ramiro Ortega-Hernandez, is incompetent to stand trial. Mr. Ortega, 21, of Idaho Falls, Idaho, is accused of using an assault rifle last month to fire on the White House in an attempt to assassinate President Obama, who was out of town. A preliminary psychiatric screening found Mr. Ortega competent to stand trial, but federal prosecutors asked for more extensive tests.