A Chinese-American woman, working as software engineer, has been found guilty by a US court of stealing trade secrets of Motorola.

Hanjuan Jin, a naturalised US citizen born in China, "criminally betrayed Motorola by stealing its trade secrets," US District Judge Ruben Castillo ruled. Jin, 41, was found guilty of three counts of theft of trade secrets.

However, in a 77-page opinion, Castillo found her not guilty of three counts of economic espionage for the benefit of the People's Republic of China and its military. She faces a maximum penalty of 10 years in prison on each count of stealing trade secrets.

Jin was arrested in February 2007 when she was trying to flee the country from the Chicago airport. At that time she had more than 1,000 paper and electronic Motorola proprietary documents in possession when she was stopped by US customs officials.

"The verdict establishes that Jin stole valuable trade secrets from an American company, and we will do everything we can to guard our economic and national security from the theft of American trade secrets," said Patrick Fitzgerald, US Attorney for the Northern District of Illinois.

According to the evidence at trial, Jin began working for Motorola in 1998, and she took a medical leave of absence in February 2006.

Between June and November 2006, while still on sick leave, Jin pursued employment in China with Sun Kaisens, a Chinese telecommunications company that developed products for the Chinese military. Between November 2006 and February 2007, Jin returned to China and did work for Sun Kaisens on projects for the Chinese military.

During this same period of time, Jin was given classified Chinese military documents by a Sun Kaisens employee to review in order to better assist with the Chinese military projects. After receiving these documents, Jin agreed to review the documents and provide assistance.

Jin returned to the US from China in February 22 and then she reserved a one-way ticket to China for a flight scheduled to depart on February 28, 2007.

The following day, on February 23, 2007, Jin advised Motorola that she was ready to end her medical leave and return to work at Motorola, without advising that she planned to return to China to work for Sun Kaisens.

On February 26, 2007, Jin returned to Motorola, purportedly to resume full-time work, and was given no assignments by her supervisor.

That day she accessed more than 200 technical documents belonging to Motorola on its secure internal computer network. During the day on February 27, 2007, Jin sent an email to her manager in which she appeared to volunteer for a layoff at Motorola.

Same night she returned to Motorola's offices and downloaded numerous additional technical documents.

As she attempted to depart on February 28, 2007, from the Chicago airport, authorities seized numerous materials, some of which were marked confidential and proprietary belonging to Motorola.

Some of the documents provided a detailed description of how Motorola provides a specific communication feature that Motorola incorporates into its telecommunications products sold throughout the world.

At the same time, authorities recovered multiple classified Chinese military documents written in the Chinese language that described certain telecommunication projects for the Chinese military. Many of these documents were marked 'secret' by the Chinese military.

Authorities also recovered approximately USD 30,000 that was in six different envelopes, each containing USD 5,000, all in hundred dollar bills, the Department of Justice said.