A former General Motors engineer with access to the car maker's hybrid technology has been convicted, along with her husband, of stealing trade secrets for possible use in China.
Shanshan Du won a transfer within GM in 2003 to be closer to the technology and then copied documents until she accepted a severance offer and left the company in 2005, prosecutors said.
Du and Yu Qin were found guilty on Friday by a federal jury in Detroit after a trial that lasted weeks.
Qin was also convicted of wire fraud and attempting to obstruct justice by shredding documents.
Prosecutors told jurors that GM trade secrets were found on at least seven computers owned by the couple.
The government doesn't believe the information ever made it to China, although Qin had set up his own company, Millennium Technology International, and claimed to have made contact with GM competitors overseas.
Defence lawyers acknowledged that GM information was in the suburban Detroit couple's possession, but they downplayed the commercial significance.
In her closing argument, Assistant US Attorney Cathleen Corken said Du was the "linchpin" in the scheme because of her job at the car maker.
"It can't happen without her," the prosecutor said on Thursday.
Corken noted that the agents kept an eye on the couple after searching their home in 2006 and watched Qin dump shredded documents in a grocery store dumpster.
"Is that the conduct of innocent people?" she asked.
Corken said the technology was worth at least $US40 million ($A38.52 million), the price that other automakers had legitimately paid GM to get it.