DETROIT (AP) — Investigators from the National Transportation Safety Board apparently have solved the mystery of why no one was found behind the steering wheel of a Tesla that crashed in a Texas two years ago, killing two men.

The agency said in an investigative report released Wednesday on the fiery April 17, 2021 crash in the Houston suburb of Spring that the 59-year-old Tesla driver apparently moved to the back seat after slamming into the car's front air bag, deforming the steering wheel in the crash.

Although the crash raised questions about whether the car was operating on Tesla's "Autopilot" partially automated driving system, the NTSB determined that the system could not have been used on the street where the crash happened due to lack of lane lines. Testing showed the car's "Traffic Aware Cruise Control" system could have been used, although it would only work up to the maximum speed on the suburban road, 30 mph (50 kilometers per hour), the report said.

The 2019 Tesla reached 67 mph (108 kilometers per hour) two seconds before hitting the second of two trees at 57 mph (92 kilometers per hour) before being consumed by flames as the lithium-ion battery caught fire.

The Tesla's event data recorder showed that the accelerator moved "consistent with driver activity" in the five seconds before the crash, and that the driver's seat belt was connected when the crash happened.

"Although the driver's seat was found vacant and the driver was found in the left rear seat, the available evidence suggests that the driver was seated in the driver's seat at the time of the crash and moved into the rear seat postcrash," the report said.

The agency found that excessive speed and failure to control the car due to alcohol impairment caused the crash. The report says testing by a Federal Aviation Administration lab found that the driver had a blood-alcohol level of 0.151 grams per deciliter, almost twice the Texas legal limit of 0.08. Two over-the-counter sedating antihistamine medications also were found in the driver's blood, according to the report.

Autopsies determined that the driver died from blunt force trauma, burns and smoke inhalation. The 69-year-old male passenger died from blunt force trauma to the torso and extremities, as well as burns, the report said.

The agency said security video from the driver's home showed the driver and passenger getting into the front seats before driving away from the home. The car traveled about 550 feet (170 meters) before leaving the road on a curve, hitting a storm sewer inlet and raised manhole, sideswiping one tree before hitting another, the agency said.