The friend of the Boeing whistleblower found dead while he was in the midst of providing key evidence regarding the aircraft manufacturer's alleged unsafe practices said he suspected he would die.

John Barnett, a 62-year-old former Boeing quality manager, died from what appeared to be a "self-inflicted gunshot wound," the Charleston County coroner said, according to CBS News. 

Barnett's body was found in his parked truck on Saturday. The truck was located outside a hotel in Charleston, South Carolina. He had been staying there while participating in a deposition for a lawsuit. In the lawsuit, Barnett alleged that Boeing engaged in dangerous operations in their aircraft assembly. 

His lifelong friend, Jennifer, said there's "no way" he killed himself, and that he predicted he might be targeted.

"I said, 'Aren't you scared?' And he said, 'No, I ain't scared, but if anything happens to me, it's not suicide," she told WCIV-TV Thursday.

Barnett spent three decades at the aircraft manufacturing giant, before retiring in 2017, citing health issues. After that, he made public his concerns over the company's safety protocols - alleging they installed subpar airplane parts and rushed aircraft production.

He then accused them of retaliating against him for speaking up.

"[Boeing] didn't like what he had to say," and wanted to "shut him up," Jennifer alleged to the outlet. "That's why they made it look like a suicide."

"I know that he did not commit suicide," she explained. "There's no way. He loved life too much. He loved his family too much. He loved his brothers too much to put them through what they're going through right now."

Boeing issued a statement following Barnett's death. 

"We are saddened by Mr. Barnett's passing, and our thoughts are with his family and friends," it said, according to the BBC.

It's unclear if Barnett's death will impact the trial, which was originally slated to begin in June.