Brian David Mitchell, the man charged with snatching Elizabeth Smart nearly eight years ago, could finally face a jury after a federal judge ruled Monday that Mitchell was faking mental illness and is competent to stand trial.  "The evidence proves that Mitchell has the capacity to assist his counsel in his defense and the ability to behave appropriately in the courtroom," U.S. District Judge Dale Kimball wrote in his 149-page ruling issued in response to a 10-day hearing last year on Mitchell's competency.  Lawyers for Mitchell said his hallmark disruptive singing in court was evidence he's mentally incompetent.  Kimball, however, called the outbreaks a "contrivance" used by the suspect to give the impression he can't control his behavior.  "Although the defense has suggested that Mitchell's singing is a psychotic response to stress, Mitchell has repeatedly demonstrated that he has the capacity to be composed and in control, even in stressful situations," the judge wrote.  Elizabeth Smart's father, Ed Smart, said he was thrilled Mitchell was found competent.  "Because he is competent; he's crazy like a fox," Ed Smart said.  He didn't think his daughter, who is serving a mission for The Church of Jesus Christ of Latter-day Saints in Paris, had heard the news.  Mitchell's federal public defender Robert Steele took issue with the ruling while acknowledging it was a "close call."  Steele said an appeal wasn't likely to succeed, and he was instead preparing for a trial expected to start later this year.  "It is our firm conviction that Mr. Mitchell is certainly mentally ill," Steele said.  "Therefore, we are prepared to go to trial with an extremely mentally ill client."  The ruling was a leap forward in a case that languished in state court as a judge twice ruled Mitchell incompetent and refused to force him to be medicated.  The U.S. attorney's office intervened in 2008, indicting Mitchell in federal court on charges of kidnapping and unlawful transportation of a minor across state lines.