Amidst several reports of Teslas in “Full Self-Driving” mode having crashes in low-visibility conditions, including one crash that killed someone, a federal road safety agency is now investigating whether the Tesla technology might be to blame.The federal National Highway Traffic Safety Administration (NHTSA) recently put out a request to all automakers about crash data involving their vehicles. We don’t know what was reported back. Except we do know what was reported back for one particular automaker, because it has led to a formal investigation by the NHTSA. As the Associated Press reports, Tesla is under investigation for four crashes that happened in “Full Self-Driving” mode, one of which killed a pedestrian.The crash that killed the pedestrian is obviously the most alarming of these, though “another crash involved an injury” too, per the AP. The fatal crash was in Rimrock, Arizona in November 2023, and it’s a heartbreaking story. The original crash did not even involve the Tesla, but two other vehicles that collided. A Toyota 4Runner stopped to help direct traffic around the scene of that crash, and the Tesla rammed into and killed one of them — a 71-year-old woman from Mesa, Arizona. The common thread between the four Tesla crashes is that they apparently all involved “Full Self-Driving” mode, and occurred under weather conditions that involved sun glare, fog, or heavy dust. The NHTSA says it's investigating whether the Tesla vehicles “detect and respond appropriately to reduced roadway visibility conditions, and if so, the contributing circumstances for these crashes.” But the investigation is broader, and will assess data from 2.4 million Teslas produced between 2016 through 2024.Unlike most self-driving cars,  Tesla self-driving technology uses only cameras, at the insistance of CEO Elon Musk, and not the laser-based light detection and ranging (LIDAR) most other autonomous vehicles employ. Since people drive using only their eyes, Musk has called self-driving with LIDAR technology a “fool’s errand.”The probe could put more than just a damper on Tesla’s much-ballyhooed robotaxi unveiling last week. At that event, the company unveiled prototypes of robotaxis without steering wheels, gas pedals, or brakes. NHTSA would have to approve of such models operating, and as the AP points out, “it’s unlikely that would happen while the investigation is in progress.” Related: Tesla In Self-Driving Mode Blamed For Eight-Car Pileup On Bay Bridge [SFist]Image: GRUENHEIDE, GERMANY - MARCH 22: Tesla CEO Elon Musk attends the official opening of the new Tesla electric car manufacturing plant on March 22, 2022 near Gruenheide, Germany. The new plant, officially called the Gigafactory Berlin-Brandenburg, is producing the Model Y as well as electric car batteries. (Photo by Christian Marquardt - Pool/Getty Images)