Tesla's Autopilot system could not have been engaged during a fatal car crash in April, according to a preliminary US investigation released Monday that did not determine the cause of crash.

The initial National Transportation Safety Board (NTSB) finding supported Tesla's statements that Autopilot was not in use, saying that a key component of the system "was not available" on the road where the crash happened.

The report also said that the owner entered the car in the driver's seat, according to video footage from the deceased motorist's home.

But the report did not directly weigh in on statements by local police that no one was found behind the wheel after the crash.

The National Transportation Safety Board finding supported Tesla's statements that Autopilot was not in use during a fatal crash in Texas
The National Transportation Safety Board finding supported Tesla's statements that Autopilot was not in use during a fatal crash in Texas AFP / Patrick T. Fallon

Tesla has expressed skepticism about the police statement on this point, saying that the deformed state of the steering wheel suggested that the driver was behind the wheel.

The crash, which killed the 59-year-old driver and a 69-year-old passenger, took place 550 feet away from the owner's residence after the car departed the road on a curve, drove over the curb and hit a drainage culvert, a raised manhole and a tree, the NTSB said.

"All aspects of the crash remain under investigation as the NTSB determines the probably cause, with the intent of issuing safety recommendations to prevent similar crashes," the NTSB said.

The crash has added to scrutiny of Tesla and its systems, prompting a pair of US senators last month to demand a federal probe of the incident.