Shepard considered this for a moment. Most likely it was another of member of the group, but who could say for certain? If that was the case, it wouldn't do much good to provoke Avarice into another violent response.

"Unfortunately I couldn't really say. You'd know better than I would. I've barely passed more than a few words with any of the people I've arrived with and I couldn't even say for sure how many of us there were. For all I know this new reading may have nothing to do with any of us and may not be important at all. Personally, I'd suggest dealing with the known issue first. Finding this Illuxion might just provide more information as to what is going on elsewhere."

And having Avarice demand even more unknowable answers from made Shepard want to ask some questions of his own.

"And while have a few moments at least I wouldn't mind at some basic information about where I am, at least as a gesture of good faith for cooperating with you. You are clearly not Geth, so I've never seen any synthetics like you before, and I'm willing to bet no one else in Council Space has either."