The exterior of the Boeing Company headquarters is seen on March 25, 2024, in Arlington, Virginia.

Editor’s Note: If you or someone you know is struggling with mental health, help is available. Dial or text 988 or visit 988lifeline.org for free and confidential support.

CNN  — 

Boeing whistleblower John Barnett died by suicide, according to a police report released on Friday, bringing to end an investigation of the shocking death of a longtime employee who raised concerns about the airplane manufacturer’s safety and production standards – and who sued the company, claiming Boeing illegally retaliated against him.

Barnett, 62, was found dead in a vehicle on March 9 from a self-inflicted gunshot wound in Charleston, South Carolina. Officers had been dispatched to conduct a welfare check on Barnett at a Holiday Inn when he failed to show up to a deposition in his case against Boeing, according to his lawyers and a police incident report.

When they arrived, responding officers found Barnett dead in the driver’s seat of a truck in the parking lot. He was holding a handgun. The initial police report also said there was a note in the truck.

But Barnett’s lawyers said in a statement following his death that his deposition was nearing an end and he appeared to be in good spirits.

“We didn’t see any indication he would take his own life. No one can believe it,” his lawyers, Robert Turkewitz and Brian Knowles, said in a statement on March 12. “The Charleston police need to investigate this fully and accurately and tell the public what they find out.”

The Charleston Police Department on Friday concluded their investigation into Barnett’s death, saying the Charleston County Coroner’s Office determined that Barnett had killed himself.

The investigation found that Barnett was shot in the head at close range and the weapon was found in his right hand. There was also a notebook found in the front seat of the car that showed signs that “he was going through a period of serious personal distress,” according to a media release about the police investigation.

Police shared with CNN an image of a note left in the car, which had multiple disparaging messages directed at Boeing.

“As this investigation comes to a close, we should not forget it represents the loss of Mr. Barnett’s life,” police said, “We extend our deepest sympathies to his family during this difficult time and hope they continue to find the strength to persevere in absence.”

Boeing could not immediately be reached for comment. In March, the company said it was saddened by Barnett’s death.

“Our thoughts are with his family and friends,” the company said.

Accusations of safety lapses

Barnett, a former quality manager who had worked at Boeing for decades, told the New York Times in 2019 that he had discovered unsafe wiring clusters in Boeing’s manufacturing processes that, if severed by nearby metal slivers, could have led to the catastrophic failure of an aircraft.

“As a quality manager at Boeing, you’re the last line of defense before a defect makes it out to the flying public,” Barnett told the Times. “And I haven’t seen a plane out of Charleston yet that I’d put my name on saying it’s safe and airworthy.”

In a statement sent to the plant’s employees and provided to CNN at the time, Brad Zaback, a site leader at the plant and general manager of the 787 program, said the Times’ report “paints a skewed and inaccurate picture of the program and of our team (at the plant).”

Zaback, who said the Times declined an invitation to visit the plant, said “quality is the bedrock of who we are,” adding that the plant delivers “the highest quality airplanes.”

Since Barnett’s initial public warnings about Boeing, the company has had several high-profile safety and quality lapses, including the blowout of a door plug on a 737 Max shortly after takeoff in January. That led the US Justice Department to announce this week that Boeing could face criminal prosecution for its history of safety problems.