A navigation mistake by Autopilot contributed to the grisly death of a Tesla Model X owner in Mountain View, California, according to a preliminary report released today by the National Transportation Safety Board.

Apple engineer Wei “Walter” Huang was traveling south on US Highway 101 on March 23rd when his Model X P100D smashed into the safety barrier section of a divider that separates the carpool lane from the off-ramp to the left. The front end of his SUV was ripped apart, the vehicle caught fire, and two other cars crashed into the rear end. Huang was removed from the vehicle by rescuers and brought to Stanford Hospital, where he died from injuries sustained in the crash.

The agency says that Huang’s hands were detected on the steering wheel for a total of 34 seconds, on three separate occasions, in the 60 seconds before impact. NTSB also confirms Tesla’s position that the vehicle did not detect the driver’s hands on the steering wheel in the six seconds before the crash. There were two visual alerts and one auditory alert for the driver to place his hands on the steering wheel, but those alerts were made more than 15 minutes before the crash.

Huang’s Model X was following a lead vehicle using adaptive cruise control and autosteer, and traveling about 65 mph, eight seconds before the crash. A second later, the Tesla began a left steering movement. Then the vehicle the Tesla had been following moved, causing Huang’s vehicle’s speed to increase from 62 mph to 70.8 mph. There was no braking or evasive steering detected prior to impact.

A Tesla spokesperson declined to comment on the preliminary report, and instead pointed to the company’s prior statement on the deadly crash. In that statement, the company said that a damaged safety barrier, called a crash attenuator, contributed to the severity. Tesla also said that Huang had “about five seconds and 150 meters of unobstructed view” of the concrete divider with the crushed safety barrier before the incident. Huang’s family has retained a law firm and is exploring their legal options, local reports say.

a left steering movement

NTSB confirms the attenuator had been damaged in the previous week when a Toyota Prius crashed in the same location. The damage likely made the attenuator ineffective and contributed to Huang’s death.

The battery from the totaled Model X began to smoke later that afternoon while in the impound lot, according to the NTSB report. “The battery was monitored with a thermal imaging camera, but no active fire operations were conducted,” NTSB says. “On March 28, [five] days after the crash, the battery reignited.” Firefighters responded and extinguished the blaze.

The report follows the decision by NTSB to boot Tesla from its investigation into the deadly crash, which the agency claims was because Tesla had released “investigative information before it was vetted and confirmed by” the agency. Tesla CEO Elon Musk also reportedly hung up on the head of the agency during a heated call concerning the investigation.

The NTSB said Tesla is still a party in two other ongoing investigations into non-fatal accidents: one from January 22nd, 2018 involving Autopilot, and one from last summer involving a battery fire. In May, Musk vowed to begin releasing a quarterly safety report about Autopilot.