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.
A conspiracy is when a group plans to do something unlawful. So if it’s proven true it’s still a conspiracy. It just stops being a theory.
A “theory” is a collection of information we currently understand to be true.
The term “conspiracy theory” is a misnomer that should be correctly expressed as “conspiracy hypothesis”. But that’s just a theory.