Do you mean the one where you ask "Do you have chat history for mid 2015?"? I do. Do you have specific search terms? There's quite a lot of chat history.
IIRC, someone was on JD claiming to be Alex from bitdice trying to buy a bunch of CLAMS, they were saying that they could confirm with Alex's bitcointalk account that it was "really" him. I believe this would have probably happened no later than July 02, 2015, 04:56:17 PM GMT when Alex regained access to his forum account.
I have no idea what he wants you to check, although I suspect that he might want you to confirm that he was not successful in taking anyone's money. Either way he would likely still be guilty of identity theft in most jurisdictions merely by trying to impersonate Alex this way.