Forget the law-evading software , the #DeleteUber protests and even the video of CEO Travis Kalanick chewing out an employee er, that is, an independent contractor.

Ultimately, Uber might be undone by the inbox.

On Dec. 13, an employee at Waymo, a self-driving startup founded by Google , was accidentally copied on an email from one of its vendors. Where was the email supposed to go? Why, to Uber or, more specifically, to Ubers newly acquired startup Otto.

Included in the email were schematics for a circuit board, one that looked remarkably similar to a board designed at considerable expense by Waymo. Without that circuit board and the LiDAR (laser-based surveying) technology it made possible, neither Otto nor Waymo would be going on a self-driving jaunt any time soon.

The email, which a Waymo employee was copied on, was titled OTTO FILES and its recipients included an email alias indicating that the thread was a discussion among members of the vendors Uber team, lawyers representing Waymo wrote in a complaint filed in court late last month .

Attached to the email was a machine drawing of what purported to be an Otto circuit board... that bore a striking resemblance to and shared several unique characteristics with Waymos highly confidential current-generation LiDAR circuit board, the design of which had been downloaded by Mr. Levandowski before his resignation.

Mr. Levandowski is Anthony Levandowski, a former Waymo engineer now at the center of a brewing showdown between Google and Uber. Levandowski abruptly resigned from Waymo in January 2016, then founded Otto and sold it to Uber for $680 million that summer. (You can read a complete, surprisingly riveting timeline of the saga here , via the New Zealand tech blogger Daniel Compton.)

The vendors misaddressed email has spurred an investigation by Waymo into Levandowskis activities. Waymo declined to speak about the email or the ensuing investigation, instead directing The Huffington Post to a company blog post on the matter :

We found that six weeks before his resignation this former employee, Anthony Levandowski, downloaded over 14,000 highly confidential and proprietary design files for Waymos various hardware systems, including designs of Waymos LiDAR and circuit board. To gain access to Waymos design server, Mr. Levandowski searched for and installed specialized software onto his company-issued laptop. Once inside, he downloaded 9.7 GB of Waymos highly confidential files and trade secrets, including blueprints, design files and testing documentation. Then he connected an external drive to the laptop. Mr. Levandowski then wiped and reformatted the laptop in an attempt to erase forensic fingerprints.

Beyond Mr. Levandowkis actions, we discovered that other former Waymo employees, now at Otto and Uber, downloaded additional highly confidential information pertaining to our custom-built LiDAR including supplier lists, manufacturing details and statements of work with highly technical information.

Adding to the intrigue, a former Waymo colleague of Levandowskis testified last Friday that Levandowski had discussed replicating the LiDAR technology at a new company, and that an Uber executive had approached him about buying the team responsible for the LiDAR we were developing at Google.