Boeing whistleblower John Barnett, who brought to light swathes of alleged safety concerns with the US aircraft manufacturer's planes, has been found dead in his truck in South Carolina.
The Charleston County coroner confirmed his death on Monday and announced that an investigation is ongoing.
Police believe that the 62-year-old died on Saturday from a "self-inflicted" wound.
In the days leading up to his death, Barnett had been giving evidence in a lawsuit against his former employer. He had worked for the firm for more than 32 years until his retirement in 2017.
In response to his death, Boeing released a statement expressing condolences: "We are saddened by Mr. Barnett's passing, and our thoughts are with his family and friends."
In the seven years before leaving Boeing, Barnett worked as a quality manager at the manufacturer’s North Charleston plant.
In 2019, he raised concerns about his former employer, claiming that over-stretched staff were being forced to cut corners.
According to his early testimony, passengers on Boeing's 787 Dreamliner planes could have been left without oxygen in the case of sudden cabin decompression.
He explained that a quarter of the plane’s oxygen systems might not work when needed because staff were encouraged to use faulty components.
In some cases, Barnett claimed that parts were even being removed from scrap heaps and attached to planes to prevent production delays.
When raising these concerns with his superiors, Barnett said there was no follow-up action.
Boeing denied these allegations, although an investigation by the US Federal Aviation Administration (FAA) later confirmed some of Barnett’s allegations.
The whistleblower retired on health grounds in 2017 but continued the battle against his former employer, who he accused of defaming his reputation and career.
Boeing also denied these accusations.
At the time of his death, Barnett was in Charleston to testify against his former employer concerning the defamation case, but alarm bells were raised when he didn’t attend a legal interview on Saturday.
He was subsequently found in his truck in the car park of his hotel.
Barnett’s death has pushed Boeing further into the spotlight at a time when the manufacturer is already facing intense scrutiny.
In January, a cabin panel came off a Boeing 737 MAX 9 plane, raising safety concerns and jeopardising client orders.
Last week, an investigation by the FAA concluded that "the company allegedly failed to comply with manufacturing quality control requirements" in numerous instances.
The FAA has given Boeing 90 days to outline its action plan.
