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.
(Interwebz pedant voice) actually there are several scenarios possible where one could conceivably kill themselves with a sniper rifle 100 yards away . . . People who don’t know about this are just so credulous, but weapons science has known for a long time that JFK actually killed himself . . .