User blog comment:Zori9/Is Vergo an imposter?!/@comment-4899461-20120911152857

In 673, Law states that when Vergo was part of DD's crew, before Vergo got famous DD had him join the marines. Law's statement of "It's not like Vergo has betrayed the marines" means that it is not like Vergo was once a fine marine, and turned on them, but more like Vergo was never really a marine to begin with. And he's not really a marine, this is why Oda didn't introduce him as a VA until a bit later.