Chi Mak, 65, of Downey was convicted in Santa Ana federal court last May on charges that he filled information wish lists provided to him by Chinese intelligence services and shipped the data to Beijing in CDs by family members.

Prosecutors said China directed Mak to attend specific technical conferences and pick up sensitive information that was subject to restrictions on its distribution.

The operation was uncovered in 2005 when one such CD was found in the luggage of a family member who was about to depart on a flight to China.

"Today's 24-year sentence is a fitting punishment for an American citizen who was convicted of working clandestinely on behalf of China in an effort to steal critical information about the U.S. Navy's current and future warship technologies," Kenneth Wainstein, assistant U.S. attorney general for national security, said in a statement issued by the U.S. Attorney's office in Los Angeles.