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.
I’d say it’s more like a huge percentage of votes for one candidate got lost in a fire. Sure fires happen, but it was really important that this one should be protected from happening.