A federal judge has ordered Uber to stop using technology that an executive downloaded before he left Google's Waymo autonomous car company.

The order filed Monday in a trade secrets theft lawsuit also forces Uber to return all downloaded materials by noon on May 31.

Judge William Alsup in San Francisco says in the ruling that Waymo has shown "compelling evidence" that a former star engineer named Anthony Levandowski downloaded confidential files before leaving Waymo. The Judge also says evidence shows that before he left Waymo, Levandowski and Uber planned for Uber to acquire a company formed by Levandowski.

Waymo sued Uber in February alleging that the ride-hailing company is using stolen self-driving technology to build its own fleet of autonomous cars. The ruling prevents Uber from using the technology on Uber's Lidar navigational tool.

Waymo had sought to shut down Uber's autonomous car program completely until the dispute is settled. But the judge determined that Waymo's patent infringement theories were too weak to support such an order.

Uber said in a statement Monday that it's pleased the court allowed it to continue self-driving car research, including its own Lidar innovations.

Google welcomed the order stopping Uber from using "stolen documents containing trade secrets developed by Waymo through years of research."

Last week judge Alsup took the rare step of referring the case to federal prosecutors for an investigation of possible criminal misconduct, deepening the turmoil swirling around the case. Prosecutors are likely to follow up on Alsup's order and launch an investigation