Waymo, the self-driving car unit of Google parent Alphabet, on Thursday filed a lawsuit against Otto and its parent company Uber over allegations of stolen technology and infringement of patents.

Otto is a startup working on self-driving technology for transport trucks and was acquired by Uber last August for approximately $600 million. Several employees at Otto including co-founder Anthony Levandowski previously worked at Waymo while it was still known as the Google Self-Driving Car Project.

In its lawsuit, which you can read here, Waymo said it uncovered evidence that Otto and Uber have taken and are using key parts of Waymo’s self-driving technology, specifically technology related to a custom lidar system. The system uses lasers to form a 3D image of a vehicle’s surrounding environment.

Otto self-driving truck prototype

Otto self-driving truck prototype

Among the evidence is an email sent by a supplier of lidar components that inadvertently copied a Waymo employee. In the email was a circuit board drawing for Uber’s lidar system, which according to Waymo shared a “striking resemblance” to its own design.

Furthermore, Waymo alleges that Levandowski and other former employees now at either Otto or Uber downloaded highly confidential information weeks before resigning. Levandowski in particular is alleged to have downloaded in the weeks before his resignation over 14,000 highly confidential and proprietary design files for Waymo’s various hardware systems, including designs of Waymo’s lidar circuit board. Waymo even alleges that Levandowski used special software on his company-issued laptop to download all the files to an external drive and then wiped and reformatted the laptop before returning it.

The lawsuit comes at a time when Uber is already dealing with allegations of sexual harassment. The company has hired lawyers including former Attorney General Eric Holder to conduct a review into the harassment allegations.