Feb. 24, 2017—Waymo, a self-driving car company owned by Google parent Alphabet, dropped a lawsuit on Uber on Thursday, alleging the ride-hailing company stole trade secrets.

The suit alleges that Anthony Levandowski, a former Google employee who founded Otto (a self-driving trucking company Uber acquired last year), downloaded 14,000 confidential files with self-driving technology research. Waymo claims that Levandowski used special software to access the files and reformatted his computer to cover his tracks. It says Uber used the information after it acquired Otto.

The suit comes just weeks after Uber announced a partnership with Daimler—the parent company of Mercedes-Benz—in developing self-driving technology.

GV, Alphabet's venture capital arm, invested in Uber in 2013. It was one of the firm's most high-profile deals.

"Our parent company Alphabet has long worked with Uber in many areas, and we didn't make this decision lightly," Waymo said in a blog post. "However, given the overwhelming facts that our technology has been stolen, we have no choice but to defend our investment and development of this unique technology."

Uber has been pursuing its own self-driving car research and pilot programs. Last year, it attempted to use self-driving cars to pick up passengers on San Francisco streets. The program was halted because the company didn't have a permit to operate self-driving cars in California.

Waymo's suit specifically calls out trade secrets related to "lidar" technology, laser arrays used in self-driving car research to detect objects in a car's environment. Waymo said it learned of the alleged theft after a vendor accidentally emailed a Waymo employee, with an attached diagram of an Uber lidar circuit board.