LOS ANGELES - An engineer at a California defence contractor and three others who authorities say are "foreign intelligence officers" for China have been arrested and charged with stealing US military secrets, according to court documents.
Federal prosecutors declined to comment on the arrest a week earlier of the two married couples, who were taken into custody at Los Angeles International Airport as they prepared to board a late-night flight for China.
An FBI affidavit unsealed this week showed Chi Mak and his wife, Rebecca Laiwah Chiu, were charged in US District Court along with Chi's brother, Tai Wang Mak and Tai's wife, Fuk Heung Li, with theft of government property, conspiracy and transportation of stolen goods.
Chi, an engineer at California-based defence contractor Power Paragon, and his wife are naturalised US citizens originally from China. Tai and his wife are legal US residents who emigrated from China in 2001.
Although none of the defendants was charged with spying, FBI Special Agent James Gaylord wrote in the affidavit he believed them to be foreign intelligence officers involved in stealing US military secrets and delivering them to the Chinese government.
Attorneys for the defendants could not immediately be reached for comment.
Chi, the lead engineer on a classified research project involving quiet propulsion systems - known as Quiet Electric Drive - for US Navy warships, is accused of taking sensitive information about the project, copying it onto CDs and delivering them to his brother, Tai.
Tai, according to the affidavit, is accused of encrypting the information and making plans to take it to China with his wife. Chiu is accused of assisting her husband in copying the material.
"Based on my experience and training, I believe the targets are foreign intelligence operatives," Gaylord wrote in asking a judge to approve a special nighttime search of their residences.
"The arrests of Tai and Fuk must take place at LAX before the targets departure ... to ensure that the disks containing the government property are retrieved before they can leave the country," he wrote.
Gaylord said in the affidavit that evidence against the four defendants included torn-up documents recovered from the trash at Chi's residence that included lists of sought military technologies as well as intercepted phone calls and e-mails.