A Kansas man is now the second whistleblower linked to Boeing to die in the last two months.
The family of 45-year-old Joshua Dean says he died April 30.
He had a staph infection that quickly developed into pneumonia.
Dean, a former quality auditor at Boeing supplier Spirit AeroSystems, was reportedly among the first to sound the alarm about potentially dangerous defects with the 737 Max.
In March, a former Boeing manager who raised safety questions about the aircraft maker was found dead from what appeared to be a self-inflicted gunshot wound.
John Barnett, 62, was a longtime Boeing employee and worked as a quality-control manager before he retired in 2017. In the years after that, he shared his concerns with journalists.
The Associated Press contributed to this report.