John Barnett, who worked for Boeing for more than three decades before blowing the whistle on the aircraft maker’s allegedly questionable safety standards, was found dead in his car in South Carolina.

Barnett, 62, was supposed to be in a deposition Saturday to answer questions related to a lawsuit against his former employer when he failed to show up to the meeting. His legal team tried to reach him by phone to no avail, until they contacted the hotel where Barnett was staying.

He was found dead in his truck in the hotel parking lot.

The Charleston County Coroner’s Office told local media that it appears Barnett died from a self-inflicted wound. The Charleston Police Department is investigating his death.

Barnett, originally from Louisiana, was in Charleston for legal interviews related to his case against Boeing, in which he argued that his former employer retaliated against him for raising concerns about the safety of the airplanes produced at its Charleston manufacturing plant.