My fear is it might have been a professional hit and if that's the case either the shooter will likely never be apprehended
I don't think it was professional. That would mean he/she was hired and paid by someone. I have no idea who this Kirk guy was, but he doesn't seem like he was worth a paid hit. Originally, I thought he was the Project Veritas guy.
I'm confident he will eventually be caught... the world is full of cameras and informants these days. Small possibility there might be diplomatic immunity involved, but I don't see it.
which were actually manufacturer's markings
LOL. I was wondering how, or why, someone would "engrave" markings on a cartridge.