I think that was a ruse LE used to try to get GG to admit to what he did. If they ask "Was so and so involved" that implicates Gabe himself as being involved if he knew someone else was involved. If they ask "Were you the only one involved?" The answer "Yes", means he did it, the answer "No" means he was involved but not the only one. It a way of getting people to speak instead of shake and nod their head.
im not sure what im allowed to say regarding this soooo i will just say that in my opinion they had reason to believe that one specific other person may have been involved(?) also just in my opinion they do not think this anymore...