US safety investigators have found that the Tesla driver involved in a fatal Texas crash manually overrode the vehicle’s Full Self-Driving (Supervised) system by fully pressing the accelerator. The finding shifts attention from whether the assistance system was active at impact to why the driver accelerated, while maintaining scrutiny of Tesla’s supervised-driving technology.

The National Transportation Safety Board said the Model 3 was travelling at more than 70mph when it struck Martha Avila’s home in June, killing her; Tesla said the recorded speed was 73mph. Driver Michael Butler said he had enabled FSD while changing music and then passed out, while investigators found no alcohol or drugs and no braking in the final minutes; he has since been charged with manslaughter, and Avila’s family is suing him and Tesla. The National Highway Traffic Safety Administration is separately investigating the crash and Tesla’s self-driving technology more broadly.