What makes you think it's him? He hasn't logged in since the 5th.
Id let it go, OP does not want to share which is his/her account, so there is nothing we can do. Yes you could (maybe) crossreference IP addresses, but if OP was actually looking for an answer and/or help he/she would post a link. Countless others have in the past and got answers. I cant judge if those have been helpfull though.