DETROIT
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A former General Motors engineer and her husband conspired to steal trade secrets about hybrid vehicles and use the information to make private deals with Chinese competitors, according to a federal indictment unsealed Thursday.

Shanshan Du and Yu Qin, both of Troy, were indicted on conspiracy and other charges. They had been under investigation for years and were charged in 2006 with destroying documents, a case that was dropped while a broader probe was ongoing.

The indictment says Du, who was hired at GM in 2000, purposely sought a transfer in 2003 to get access to hybrid technology and began copying documents by the end of that year.

In 2005, she copied thousands of documents, five days after getting a severance offer from the automaker, according to the indictment.

By that summer, Qin was telling people that he had a deal to provide hybrid technology to Chery Automobile, a GM competitor in China, the indictment says. He had set up his own company, Millennium Technology International.

"Theft of trade secrets is a threat to national security," Andrew Arena, head of the FBI in Detroit, said in a statement.

Du and Qin were due in court to hear the charges Thursday. A message seeking comment was left for Du's lawyer.