We have similar ones to this in our area, but they are black and this guy was a definite metallic dark blue. Also he had pale yellow/cream feathery things on his antennae and some kind of maroon/brown "spurs"
One of the researchers was collecting insects around the gardens -- he let me look through a few of the bugs he collected.
https://www.inaturalist.org/journal/sambiology/25760-costa-rica-wow