Frankly I don't believe either one of you. The simplest explanation is the most likely, which is the account was sold & the original owner is trying to take it back.
Yeah, it seems like it. I first thought OP had a case until I read the post from the current account holder.
The one who owns the account currently has no proof of ownership:
Alright friends, you can now consider whatever you think is trustworthy. You can't force me to sign messages from the same bitcoin address the OP has, now only he has it. I also don't design signatures and logos, that's not my skill, it's a skill I paid for in the past.
And the one who has the proof of ownership seems confused:
The fact is, my close friend, student in same university, created this account to me and give it to me to explore bitcointalk and doing postings and finally find design contests that suitable with my skill. He said I have full control of it and we share the password and username as we trust each other. BUT, after I find out the account is not under my control anymore, I tell my friend but he said he don't know. Tell me, is that you my friend? If so, why you don't tell me before?
Edit: If you are really my friend, tell me the initial letter of city our university.
So, what should be the solution for this case? I would say, the account in question,
Falconer, should get red-tagged by a bunch of DT members and should be left like that. This way, OP won't get the account back, and the current owner won't be able to use it for anything, unless, of course, one of them manages to
actually prove they are the original owner of the account.