This seems to line up, and if he responds making a claim that the account isn't his, then I have another solution to determining if he's telling the truth or not. First I'll issue a DNT while we await his reply. @Crystalaxe Care to elaborate here?
Also that e-mail appears to link to a previous account recovery report.
Things that could help:
1) A screenshot of any Sythe PM's
2) Proof of contacting the seller (although not necessary)
Honestly that's about it seeing as I've found some information already myself, however if I need more I'll tag you / ask you on the report. For now we'll await his reply in the meantime. If you have any further questions / concerns, then you're more than welcome to PM me.