Tesla executive Matthew Schwall has left the company for rival Waymo, The Wall Street Journal reported on Saturday. According to his LinkedIn page, Schwall has been at Tesla since 2014 and serves as "Tesla's primary technical contact with safety regulatory agencies such as NHTSA and the NTSB."

The National Highway Traffic Safety Administration sets auto-safety rules, while the National Transportation Safety Board focuses on investigating accidents. Schwall's departure comes at a time of growing tensions between NTSB and Tesla over an Autopilot-related crash—and shortly after NHTSA downplayed its own 2017 finding that seemed to vindicate Autopilot's safety record.

This might be a coincidence, according to The Wall Street Journal. "A person familiar with his move said it was unrelated to issues Tesla is dealing with regarding Autopilot," the Journal reports. But Tesla's increasingly troubled relationship with federal agencies must have been on Schwall's mind as he weighed whether to take a new job at Waymo or keep his position at Tesla.

Tesla and the feds haven't always seen eye to eye

Schwall was Tesla's liaison to the National Highway Traffic Safety Administration during the agency's investigation into the 2016 death of Tesla customer Josh Brown in Florida. Autopilot was engaged during the crash, and Schwall was the author of Tesla's August 2016 letter supplying data on the performance of Autopilot across the entire Tesla fleet.

Using that data, NHTSA reported in 2017 that serious crashes declined 40 percent after Autopilot's Autosteer feature was activated. Tesla was delighted; the company cited this finding twice in the wake of the Autopilot-related death of Walter Huang in Mountain View in March of this year.

But critics have questioned the rigor of the finding. They pointed out that another driver-assistance technology—automatic emergency braking—was activated a few months before Autosteer and may be the real reason that crashes declined. And they pressured NHTSA to release the data underlying the finding so that independent experts could reproduce it.

Earlier this month, NHTSA essentially threw Tesla under the bus. In a statement to Ars Technica and other media outlets, the agency wrote that it "did not assess the effectiveness" of Autopilot and had merely performed a "cursory comparison" to decide whether further investigation was required. The statement will make it tricky for Tesla to continue citing the figure in the future.

Meanwhile, Tesla has had a frosty relationship with NTSB in the last couple of months. NTSB offers carmakers the opportunity to become party to investigations involving its vehicles. That gives them access to information the NTSB gathers before it becomes available to the public. But in exchange, the agency requires carmakers to avoid releasing information about an accident while an investigation is underway.

But Tesla chafed under those rules in the Walter Huang case. In a blog post a week after that crash, Tesla reported that "the driver had received several visual and one audible hands-on warning earlier in the drive, and the driver's hands were not detected on the wheel for six seconds prior to the collision."

A couple of weeks later Tesla put out a media statement arguing that "the only way for this accident to have occurred is if Mr. Huang was not paying attention to the road."

NTSB responded by booting Tesla from the Huang investigation. When Chairman Robert Sumwalt called Musk to inform him of the decision, Musk hung up on him.

We imagine that Musk's confrontational approach to dealing with federal officials put subordinates like Schwall in a difficult position. There were undoubtedly other factors that contributed to Schwall's decision to take a new job at Waymo. But not having to worry about being caught in the crossfire between Musk and the feds must have been a point in Waymo's favor.

The news of Schwall's departure came a day after The Wall Street Journal reported that Doug Field, one of Tesla's most senior engineers, was taking a weeks-long sabbatical from the company. Last month, Tesla lost its third Autopilot chief in 18 months.