High winds blew over an oceanside bluff on the afternoon of October 13, 2005, as a caravan of government vehicles with agents from the FBI and Air Force descended on a stately home overlooking Uaoa Bay on Maui’s North Shore. Fifteen agents divided into two teams wearing standard raid gear—khaki pants, body armor, holstered sidearms—took positions at the sides of the house while another group approached the front door.

Special Agent James Tamura-Wageman, the search team leader, knocked. He watched through a window as a woman with a dog approached. Tamura-Wageman, from the agency’s Honolulu office, was part of a foreign counterintelligence squad. For over a year, the team had been monitoring the property—a luxury Mediterranean-style four-bedroom with a blue tiled roof and ocean and cliff views in ...