LOS ANGELES – A federal grand jury on Wednesday indicted a mother and son on charges of helping a Chinese-American engineer who allegedly tried to send sensitive information about Navy warships to China.

The indictment returned by a grand jury in Santa Ana charged Fuk Heung Li, 48, and her son,Yui “Billy” Mak, 26, with making false statements and acting as agents of a foreign government, namely China, without prior notification to the U.S. attorney general, said FBI spokeswoman Laura Eimiller.

Yui “Billy” Mak is the nephew of Chi Mak, who allegedly took computer disks from an Anaheim defense contractor where he was lead engineer on a sensitive research project involving propulsion systems for Navy warships. Ms. Li is married to Chi Mak’s brother, Tai Wang Mak, also a defendant.

Wednesday’s superseding indictment retained the original charges against Chi Mak, 65, his wife, Rebecca Laiwah Chiu, 62, and Tai Wang Mak, 56. Each faces a count of failing to register as a foreign agent.

“We continue to maintain our clients’ innocence,” said Chi Mak’s attorney, Ronald Kaye. “The government has overstated the evidence and misconstrued what was stated by my client.” John Early, attorney for Tai Mak, pointed out his client had not been charged with espionage despite the allegations in the case.

The government claims that Chi Mak, who is an American citizen, passed the information to his brother. Yui “Billy” Mak then helped encrypted the files onto CD-ROM computer disk. That disk was found hidden the luggage of Tai Mak and his wife after they were arrested in October at Los Angeles International Airport as they prepared to travel to Hong Kong and Guangzhou, China, authorities said.