The parents of a college student killed in a Tesla crash say she was trapped in the car as it burst into flames because of a design flaw that made it nearly impossible for her to open the door, according to a lawsuit filed Thursday.

The parents of Krysta Tsukahara allege that the company that helped Elon Musk become the world’s richest man knew about the flaw for years and could have moved fast to fix the problem but did not, leaving the 19-year-old arts student trapped amid flames and smoke that eventually killed her.

Tesla did not immediately reply to a request for comment.

The new legal threat to Tesla filed in Alameda County Superior Court comes just weeks after federal regulators opened an investigation into complaints by Tesla drivers of stuck-door problems. The probe and suit come at a delicate time for the company as it seeks to convince Americans that its cars will soon be safe enough to ride in without anyone in the driver’s seat.

Tsukahara was in the back of a Cybertruck when the driver who was drunk and had taken drugs smashed into a tree in a suburb of San Francisco, according to the suit. Three of the four people in the car, including the driver, died. A fourth was pulled from the car after a rescuer smashed a window and reached in.

The lawsuit was first reported by The New York Times.

Tesla doors have been at the center of several crash cases because the battery powering the unlocking mechanism can be destroyed in a fire and the manual releases that override that system are difficult to find.

The lawsuit follows several others that have claimed various safety problems with Tesla cars. In August, a Florida jury decided that the family of another dead college student, this one killed by a runaway Tesla years ago, should be awarded more than $240 million in damages.

The National Highway Traffic Safety Administration, which opened its stuck-door investigation last month, is looking into complaints by drivers that after exiting their cars, they couldn’t open back doors to get their children out and, in some cases, had to break the window to reach them.

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