Recruiting did close some time ago, but we are still at that point in the story where characters can show up late and think "...what the hell happened here"
So if you throw Inquisitor Cortez out there: A) do you have any fluff already putting her in a particular Segmentum? B) what motive would she have to come along? C) how adverse are you to pitting her against the likes of Zagan and Goruvich?
Actually, that applies to any character you put forward, so basically, convince me. Just remember that you should be willing to bring more to the table than "laspistol / stubber / sword" which, to be honest, is the rough level of what I've seen on some (woefully underpowered) Inquisitors on the Rules Discussion board.
Putting that in perspective: Holst brought a Dominator-class cruiser to the party, but on a personal level he's on the low end of the scale in terms of how much kit he's brought along. Hallona gets a pass on how little she's carrying because Marco made a note that she can steal or improvise weapons as needed (though the conversion field is entirely appropriate!), Semplice gets a pass because he's physically crippled and needs Iota et al. to do the fighting for him, and Ambrose gets a pass based on him being a
Combat Medic.
In realistic terms, consider this an order to break out the bolt pistols, the flamers, the power swords.

EDIT: Updated the GM character list on page 2.
EDIT THE SECOND: Just hunted around for Inquisitor Cortez on the P&M board. I'm fairly satisfied that this won't be a case of "laspistol/stubber/sword"
