John Barnett, a former Boeing employee known for raising technical concerns about Boeing's manufacturing standards and defects, was found dead in his car in the parking lot of the hotel where he was staying in South Carolina.

Barnett's body was found after he failed to appear in court to testify in a lawsuit against Boeing.

The coroner's office in the US state of South Carolina confirmed that the 62-year-old former Boeing employee died on Saturday. 

John Barnett, who drew attention to safety violations at Boeing factories, was found in his vehicle "with a gunshot wound to the head," a coroner's official said.

Boeing issued a statement saying it was "saddened by the passing of Barnett," who worked for the company until 2017. 

Since 2010, Barnett had worked as a quality manager at the North Charleston plant that produces the 787 Dreamliner, which is mainly used on long-haul routes.

Barnett, who worked at Boeing for 32 years, stated that in 2016, while working at the company's factory in South Carolina, he found that a quarter of the emergency oxygen systems were not working properly and oxygen masks did not come out at the right time during quality control tests on the "787 Dreamliner".

Barnett noted that he had requested further testing to understand the manufacturing defect in the systems in question, but that this request was blocked by Boeing executives.

Barnett stated that he filed a complaint with the US Federal Aviation Commission (FAA) in 2017 and claimed that the organization did not take any steps to find a solution.

In 2019, John Barnett also claimed that there was a manufacturing defect in most of the systems that automatically open the oxygen masks on the passenger seats in the event of a sudden drop in cabin pressure on "787 Dreamliner" type passenger aircraft. 

In a statement to the media in 2019, the former Boeing employee said that workers under pressure were deliberately installing substandard parts on airplanes on the production line.