Federal investigators from the National Highway Traffic Safety Administration have demanded automaker Tesla hand over details about a fatal May crash that occurred while a car was in autopilot mode. NHTSA, in a letter sent Friday to the car company, asked for all documentation related to the crash that killed Joshua David Brown, 40, of Canton, Ohio, in Williston, Fla., on May 7. The agency also requested information regarding the programming and manufacture of Tesla's Automatic Emergency Braking system, a product designed to assist autopilot and prevent frontal collisions. Tesla's responses are due back to the federal authorities in part by July 29 and in part by Aug. 26. The company could face $21,000 in fines per day if it is late. "This is a huge moment," Kelley Blue Book analyst Michael Harley said.