Soundbust11
(Correction! The Kel'Shir actually can prove it because, if you take a quick look at their faction page, they have Psionics and by the words of Cat, they can reconstruct the scene from the memory of the diplomat. Yes, I know, it doesn't exactly align with your view of the Cosmoverse that well however it has been a well established fact since the better part of September 2017.)