All guessing, no hard evidence.
Given, according to my relative, the cracker-jack teams ready and able to go instantaneously to any spot on the globe to
THOROUGHLY REMOVE *ALL* HARD EVIDENCE
it shouldn't be surprising that it's hard to come by.
However, THE DISCLOSURE PROJECT of Dr Stephen Greer's DVD's set up for the congressional briefing--are quite eye-opening for any fair-minded person ready to listen to significant serious representatives of the 400+ professionals as witnesses who've gone on record about the topic.