Federal investigators want more answers from Tesla after a deadly crash involving the car maker's technology.

FOX's Dave Anthony reports:

How does Tesla's autopilot work? The national highway traffic safety administration wants to know. Asking the electric car maker for details and data on all crashes that occurred when the system did not work as expected. 

This after what happened May 7th, when a Tesla smashed into a turning semi-truck in Florida, killing the car's driver. The Tesla's cameras failed to distinguish between the truck's white side and the brightly lit sky. So the car didn't automatically apply the brakes.

Tesla says it's semi-autonomous system is an assist feature, not a self-driving car. Requiring drivers to keep their hands on the wheel, prepared to take control at any time.

Dave Anthony, FOX News