The U.S. attorney's office says the 53-year-old Margate man, Sang Ngoc Ung, came to Seattle threatening family members over a $20,000 debt.
He's suspected of setting fire to a home in the early morning hours of June 10, forcing a family to flee through a window.
Shortly after, fire investigators went to a second home associated with the family and found a destructive device that had failed to ignite. Ung is charged in connection with that device.
He was arrested Monday by Seattle police and agents with the Bureau of Alcohol, Tobacco, Firearms and Explosives. He was scheduled to make his first court appearance Tuesday in federal court.