A prosecutor in Arizona has decided not to press charges against Uber in the March 2018 death of Elaine Herzberg. One of Uber's self-driving cars crashed into Herzberg as she crossed a multi-lane road in Tempe, Arizona.

"After a very thorough review of all evidence presented, this office has determined that there is no basis for criminal liability for the Uber corporation," wrote Yavapai County Attorney Sheila Sullivan Polk in a letter dated Monday.

Tempe is in Maricopa County, not Yavapai County. But Maricopa County once collaborated with Uber on a public safety campaign. So prosecutors referred the case to Yavapai County to avoid any potential for a conflict of interest.

While Uber appears to be off the hook, Uber driver Rafael Vasquez could still face criminal charges. Dashcam video showed Vasquez repeatedly looking down at her lap in the final minutes before the crash—including five agonizing seconds just before her car struck Herzberg. Records obtained from Hulu suggest that Vazquez was streaming the television show The Voice just before the fatal crash.

Yavapai County Attorney Polk said she didn't have enough information to decide whether it would be appropriate to charge Vasquez. She encouraged Maricopa County to hire an expert to analyze video footage from the crash to determine "what (and when) the person sitting in the driver's seat of the vehicle would or should have seen that night given the vehicle's speed, lighting conditions, and other relevant factors."

Uber avoided a potential lawsuit from Herzberg's family by settling with them days after Herzberg's death.

“We shouldn’t be hitting things every 15,000 miles”

The National Transportation Safety Board has also been investigating the March 2018 crash. NTSB is strictly an investigatory agency—it doesn't have the power to prosecute anyone. But the agency issued a damning preliminary report about the crash last May.

"Emergency braking maneuvers are not enabled while the vehicle is under computer control, to reduce the potential for erratic vehicle behavior," the NTSB reported. "The vehicle operator is relied on to intervene and take action." However, "the system is not designed to alert the operator" if an emergency braking action is needed.

And we now know that a whistleblower warned about safety problems with the self-driving program just days before Herzberg's death.

"A car was damaged nearly every other day in February," wrote Robbie Miller in a letter to several Uber executives. "We shouldn't be hitting things every 15,000 miles."

Miller wrote that, after one November 2017 incident, he felt a significant accident report was not receiving enough attention. He raised the issue with "several people" in the testing program. However, he wrote, they "told me incidents like that happen all of the time."