SALT LAKE CITY -- A federal appeals court on Thursday interrupted the trial for the man accused of kidnapping Elizabeth Smart to rule on a defense motion demanding that it be moved out of Utah.

A three-judge panel of the 10th U.S. Circuit Court of Appeals in Denver agreed to take up the question of whether Brian David Mitchell can get a fair trial because of publicity his lawyers say has tainted the jury pool.

Appeals court clerk Betsy Shumaker told The Associated Press the trial is on hold pending a ruling by judges Deanell Tacha, Timothy Tymkovich and Jerome Holmes.

U.S. District Judge Dale Kimball interrupted opening statements in the Salt Lake City and sent home the jurors that he impaneled only about an hour earlier.

"I'm of course very unhappy about this," Kimball told the jury of nine men and five women, before apologizing and releasing them for the day.

"I have to do what the 10th Circuit says. I don't know what they'll do when they consider it, but for today we're in recess for this matter. I'm very sorry."

News of the appeals court's decision came just as Mitchell's defense attorney, Parker Douglas, had begun his opening remarks. It was unclear how quickly the court might rule or when the trial might resume.

Elizabeth Smart's mother and her sister Mary Katherine, who was sleeping in the same bed with Elizabeth when she was taken at knifepoint, were at the courthouse and prepared to testify Thursday.

Elizabeth Smart will also give a lengthy, detailed testimony about her abduction, the alleged sexual abuses she suffered during nine months of captivity and about the threats she says Mitchell made on her life and her family, federal prosecutors Felice John Viti said Thursday.

If convicted, Mitchell could spend the rest of his life in prison.

Smart was 14 when she was snatched from her bedroom in June 2002. She was found with Mitchell nine months later. He was accused of slicing through a kitchen window screen with a knife and whisking away the young girl in the middle of the night.

Federal prosecutors took over the case after state proceedings were stalled by questions about Mitchell's mental health. He was diagnosed with a delusional disorder and deemed incompetent to stand trial.

A state judge rejected a request to force Mitchell to be treated with medications, saying she didn't believe the drugs would work. The ruling left Mitchell incarcerated in the state hospital, where he had refused treatment.

But Kimball ruled Mitchell was competent to stand trial in March. His attorneys have said they were prepared to claim Mitchell was insane at the time of the abduction. They point to a 27-page manifesto drafted by Mitchell -- "The Book of Immanuel David Isaiah" -- as evidence of his delusions.