A former quality manager at Boeing who became a prominent whistleblower and raised concerns over the planemaker’s production line has been found dead.

John Barnett died on Saturday from what appeared to be a self-inflicted gunshot wound, according to officials in Charleston, South Carolina.

The Charleston police department is investigating. “We understand the global attention this case has garnered, and it is our priority to ensure that the investigation is not influenced by speculation but is led by facts and evidence,” it said.

Barnett, 62, retired in 2017 after almost three decades at Boeing. After finding clusters of metal slivers hanging over flight control wiring on several planes, Barnett said he urged his bosses to remove them. Instead, they moved him to another part of the company’s plant in North Charleston.

After filing a whistleblower complaint with regulators, Barnett made his concerns public in 2019, when he was one of several whistleblowers featured in a New York Times story about concerns over safety lapses at Boeing’s North Charleston site.

Boeing pushed back against his accounts.

“We are saddened by Mr Barnett’s passing, and our thoughts are with his family and friends,” the company said on Tuesday.

Boeing is now grappling with its biggest safety crisis since the crashes of two of its 737 Max 8 jets, in 2018 and 2019, in which 346 people were killed. A brand-new 737 Max 9 jet was forced into an emergency landing in January after a cabin panel blowout during an Alaska Airlines flight.

Regulators grounded 171 Max 9 aircraft for several weeks, and are still inspecting the planemaker’s production line. Boeing’s CEO, Dave Calhoun, has acknowledged the company faces a “serious challenge” to win back the confidence of officials and airlines.

Earlier this month, however, Jennifer Homendy, chair of the National Transportation Safety Board, revealed that Boeing had declined to tell investigators who worked on the door plug that blew off during the Alaska flight, and had yet to provide documentation about a repair job that included removing and reinstalling the panel.

“It’s absurd that two months later we don’t have that,” Homendy told a Senate committee. “Without that information, that raises concerns about quality assurance, quality management, safety management systems” at Boeing.

The company later stressed it had “deep respect” for the agency. “We have now provided the full list of individuals on the 737 door team, in response to a recent request,” Boeing said. “With respect to documentation, if the door plug removal was undocumented there would be no documentation to share.”

While concerns have focused on the Max program, an incident onboard a Boeing 787 this week has broadened scrutiny. The pilot of a Latam Airlines flight from Sydney to Auckland reportedly said he temporarily lost control of the jet amid a sudden drop that threw passengers around the cabin.

Brian Jokat, a passenger, told CNN he woke up as the plane “dropped something to the effect of 500 feet instantly”.

After landing, Jokat said the pilot told him that the gauges “went blank”, and that “for that brief moment he couldn’t control anything”, before the gauges returned and the flight continued as normal. At least 50 people are said to have been hurt, with 10 passengers and three cabin crew members taken to hospital.

Boeing said it is “in contact” with Latam and “stands ready” to support an investigation into what happened. “We are thinking of the passengers and crew from Latam Airlines Flight 800, and we commend everyone involved in the response effort.”

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