U.S. safety regulators have opened a special investigation into a Tesla Model 3 crash in Katy, Texas, that killed a 76-year-old woman after the car struck a home.

Authorities say the driver claimed he was using Tesla’s partially automated driving system, though Tesla executives argue he may have manually overridden the system and accelerated before the crash.

The incident is being reviewed as part of a broader pattern of federal investigations into Tesla’s Autopilot and Full Self-Driving systems, which have faced scrutiny over safety and marketing claims.

Elon Musk and Tesla have pushed back on the allegations, while officials emphasize that the findings are still preliminary and unverified, CNBC has reported.

The probe adds to ongoing concerns about the safety of automated driving technology as Tesla continues its push toward fully autonomous vehicles.