By Rebecca Elliott

Federal safety officials have raised fresh questions about a fatal April crash involving a Tesla Inc. car, including doubts that the vehicle's driver-assistance feature could have been engaged and whether an early assumption that nobody was at the wheel at the time of the incident was correct.

The National Transportation Safety Board said in a preliminary report issued Monday that the vehicle owner's home-security system showed one of the victims entering the driver's seat of the Model S sedan and the other entering the front passenger's seat at the start of the ride.

Local officials in Texas had said that one of the men was found in the front passenger's seat and the other in the back seat. The local constable's office said, based on its early investigation, that it was highly likely the vehicle didn't have anyone in the driver's seat at the time of the crash, spurring questions about how that may have unfolded. The NTSB's report didn't address when or how the men might have moved within the vehicle once the trip began.

The vehicle traveled about 550 feet before driving over a curb, hitting a drainage culvert, a raised manhole and, eventually, a tree, damaging the front of the vehicle's lithium-ion battery case, the NTSB said.

The agency said that the resulting fire damaged a module that can record data tied to information such as vehicle speed, air-bag deployment and whether seat belts were buckled. The NTSB said it had taken the device to a lab for further analysis. Another onboard storage device that could yield clues about what happened was destroyed by the fire, the NTSB said.

The agency said that a test at the crash location with a representative vehicle showed that one of the features that would have been needed to activate Tesla's advanced driver-assistance system, known as Autopilot, wasn't available in that area.

The NTSB's initial report echoes statements from Tesla last month about the crash. A Tesla executive said during an earnings call that the company had conducted a study along with authorities in which it tried to replicate the likely crash scenario. The company said that a driver assistance feature that helps with steering didn't engage in the test, while another feature, adaptive cruise control, only activated when a driver was buckled in and traveling at above 5 miles per hour.

The executive also said the car's steering wheel was found to be deformed, "leading to the likelihood that someone was in the driver's seat at the time of the crash." He didn't provide details about how the company came to that conclusion. All the seat belts, post crash, were found to be unbuckled, he said.

Tesla didn't immediately respond to a request for comment on the NTSB's preliminary report.

The NTSB said it was continuing to collect data on the crash, including the dynamics of the incident, postmortem toxicology test results, seat belt use, occupant egress, and electric vehicle fires. "All aspects of the crash remain under investigation," it said, adding it planned to issue a final report with safety recommendations to prevent similar crashes.

Write to Rebecca Elliott at rebecca.elliott@wsj.com

(END) Dow Jones Newswires

05-10-21 1541ET