In a somewhat surprising turn of events this week, Uber's General Counsel Salle Yoo sent self-driving car division executive Anthony Levandowski a sternly worded letter, dated May 15, asking him to waive his Fifth Amendment rights in the ongoing legal proceedings with competitor Waymo or else face termination at the company. As Recode reports, regarding the 14,000 files allegedly taken from Google servers prior to his departure from the company, the letter asks Levandowski to "comply with the court’s order to turn over his personal device as well as any downloaded materials he has and the names of all those he ever communicated about these files with."

The letter marks a shift in tone for Uber, which asked Levandowski to voluntarily recuse himself from running the self-driving car operation until the court proceedings are resolved, but has otherwise seemed to have his back. It's been widely discussed that Levandowski and Uber CEO Travis Kalanick are close friends and that they had been before Levandowski decided to join the company early last year.

The lawsuit, brought by Waymo/Alphabet in February, alleges that Levandowski stole trade secrets and brought them to Uber when he took a job, and last week the federal judge in the case referred it to the US attorney for potential criminal prosecution.

Uber has contended that they created their own self-driving technology, and indeed they had a team working on the project at Carnegie Mellon University before Levandowski came on board. But the case centers on Levandowski's alleged theft of a trove of blueprints and documents relating to the LiDAR technology that he helped develop while at Google. Prior to taking the full-time position at Uber, Levandowski also sold his self-driving trucking startup Otto to Uber for $680 million.

U.S. District Judge William Alsup previously chastised Uber for using Levandowski's Fifth Amendment excuse to cover themselves, saying that as his employer they could easily compel him to testify and turn over the documents.

In the letter, Yoo writes, "While we have respected your personal liberties, it is our view that the court's order requires us to make these demands of you."

According to the Associated Press, Levandowski has separately filed a request with the judge asking that his order be revised. It reads, "It is an act by the judicial branch of our federal government compelling an individual to choose between preserving his livelihood and preserving his constitutional rights."

Read the full letter to Levandowski here.

Previously: Judge Refers Waymo V. Uber Case For Possible Criminal Investigation