Former Apple Inc. engineer Xiaolang Zhang pleaded guilty Monday to theft of trade secrets from the company’s self-driving vehicle program. According to filings with the US District Court for the Northern District of California, Zhang admitted to one count of trade secret theft.

The case dates back to 2018 when Zhang was indicted for stealing a confidential 25-page document detailing circuit board designs from Apple’s nascent autonomous vehicle program.

In April 2018 Zhang tendered his resignation to Apple, citing concerns about his ailing mother in China and the need to be closer to her. According to an affidavit that Apple filed, the company learned that Zhang went to work for XPeng Motors, a startup at the time involved in electric vehicles and autonomous vehicle technology. In the affidavit, Apple alleged that Zhang’s network activity in the three days prior to his resignation increased notably compared to his previous years of employment. The affidavit contended that the majority of the increased activity consisted of Zhang downloading information from project databases that contained trade secrets.

Zhang later purchased a last-minute round-trip ticket to China. However, federal agents stopped and arrested Zhang at the San Jose International Airport after he had passed through the security checkpoint.

Subsequently, Zhang was arraigned before a magistrate, and a federal grand jury in San Jose officially indicted Zhang for theft of trade secrets. Zhang had initially pleaded not guilty.

The district court ordered Zhang’s plea agreement to be filed under seal from public view and fixed November 14, 2022 as the date for sentencing.