likely just an amateur.  you can make a suppressor fairly easily with nothing more than a hand mill, but likely a basic cnc. most homemade suppressors aren't going to have the correct baffle length or ogive, so won't cycle properly on a small caliber. especially if he was using subsonic. if he was reeeally amateur, he had a form 4 suppressor. but a glock 19 notoriously sucks with anything more than a 5 baffle and any material heavier than aluminum.  somebody performing a hit on a high level official would also know that a suppressor for close range is rather pointless, security and civilians are too close for it to make any difference. surveillance all around and much more intense scrutiny around restricted items. a professional would have waited for him at a public location he'd previously scouted with high probability of close exit and either enough for traffic to conceal, or low enough for traffic to form a perimeter, but close enough to a quick exfil location that last location would be hard to track. the fact that he immediately moved to a low traffic/ high surveillance area shows lack of trade craft or experience.  professional also would have kept brass and hand loaded something guaranteed to chamber correctly. he would have left the murder weapon or immediately tossed it before exfil on a planned route.  likely just some pissed dude who wanted revenge for something, and i don't think anybody will be surprised with the current state of corporate oligarchy that these types of attacks are becoming more common.
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