Ok, going back to this...

Burt recognizes a level 3 ID from Raydon Labs and knows that you have to be pretty smart to get one of those. Episode 42-2 struck me that Burt recognizes Austin McKibbon from a photo in the notes as one of the Beheomoths. Maybe Burt is just awesome with faces. He did get a good look at it while playing toro toro bull fighter. But, it is my experience that it is hard to recognize someone out of context.

The drugs used to Make the special zombies may have come from Raydon Labs. Does Burt's familiarity with the lvl 3 ID also give him insights into the work being done there? Does it provide that little extra context to help him recognize the human he (special zombie) once was?