John Barnett had worked for Boeing for 32 years, until his retirement in 2017.
In the days before his death, he had been giving evidence in a whistleblower lawsuit against the company.
Boeing said it was saddened to hear of Mr Barnett’s passing. The Charleston County coroner confirmed his death to the BBC on Monday.
It said the 62-year-old had died from a “self-inflicted” wound on 9 March and police were investigating.
They don’t gain much. The FAA is breathing down their neck already.
The FAA has allowed this mess to continue for far too long because Boeing is an industry titan. Too big to fail. Well, maybe not anymore.
Watch politician holdings of Boeing stock.