A prominent Boeing whistleblower who reported on safety and quality control concerns in the company’s production line was found dead Saturday, according to South Carolina authorities.

John Barnett, 62, died of an apparent self-inflicted wound on Friday, the Charleston County Coroner’s office said. He was found in his truck at his hotel’s parking lot.

A 32-year veteran of Boeing, Barnett’s 2019 whistleblower allegations claimed that overworked employees at its South Carolina plant frequently fitted substandard parts on planes and reported faulty oxygen systems that could result in as many as 1 in 4 oxygen masks not operating properly.

Boeing denied Barnett’s claims, but a follow-up investigation by the Federal Aviation Administration lent credence to some aspects of his allegations. A report found that more than 50 “non-conforming” parts were unable to be traced and were lost in the company’s system.

Barnett was in Charleston to be questioned for a long-running retaliation suit against the company.

His death comes as Boeing is under increased regulatory scrutiny for its 737 Max aircraft manufacturing process after a door blew out of a flight midair in January. The incident launched a widespread investigation into Boeing manufacturing, discovering lax quality control.

Barnett’s claims were not related to the 737 Max or the Washington manufacturing plant involved in the scandal.

“We are saddened by Mr. Barnett’s passing, and our thoughts are with his family and friends,” Boeing said in a statement to NewsNation Tuesday.

Robert Turkewitz and Brian Knowles, Barnett’s lawyers, called their client a “brave, honest man of the highest integrity.”

“John was in the midst of a deposition in his whistleblower retaliation case, which finally was nearing the end. He was in very good spirits and really looking forward to putting this phase of his life behind him and moving on,”they told NewsNation in an email. “We didn’t see any indication he would take his own life. No one can believe it.  We are all devasted. We need more information about what happened to John. The Charleston police need to investigate this fully and accurately and tell the public what they find out. No detail can be left unturned.”