So I haven't followed this super closely, but am I correct that 100% of his testimony is hearsay? In other words, he is relating what others have told him but has not personally seen the ships or aliens? If so, then it really doesn't matter how credible *he* is. He could 100% believe the things he has been told, but those things may still be untrue because the person he talked to was confused, crazy, combining elements of truth with speculation or exaggeration, etc.
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Edit here: Also, keep in mind that it's been ~80 years since the world superpowers had the opportunity and incentive to put their most top-secret tech on display for the world to see. We don't know what's locked up in research labs. It's entirely possible that this guy talked to someone who knew we had recovered wild and unexplained technology but drew an incorrect conclusion that the tech was extraterrestrial.
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It sounds like they have the wrong guy testifying. Give us the names of the people you talked to, who claim to have first-hand knowledge, and let's get them under oath.