A former General Motors engineer and her husband should be convicted of stealing trade secrets related to hybrid-car technology to help develop such vehicles in China, a US prosecutor said at the end of their trial.

Shanshan Du copied the company's private information on the motor control of hybrids and provided documents to her husband, Yu Qin, the Government alleges. Qin allegedly used the confidential data to seek business ventures or employment with GM's competitors, including the Chinese automaker Chery Automobile.

"Theft is at the heart of this case," prosecutor Cathleen Corken said in federal court in Detroit in closing arguments. Acquiring the GM information was "purposeful, deliberate and criminal".

Both defendants have pleaded not guilty. Their lawyers argued the information wasn't trade secrets, wasn't stolen and was useless for other companies.