Ask HN: Someone has hacked my Wife's Gmail Account, how can I track him?

It's 6:00 am in Germany, my wife's sleeping and after 10 minutes of work, her Gtalk icon appear on my sidebar showing her online, off and back online again for several minutes now, since I know, nobody else has her Gmail credentials and she's sleeping. How can I find out who it is, I suspect someone somehow close to her in someway, Colleauge, friend...any Idea? I know about the last activity option of Gmail that shows the location of the last activity. Is there any other option to track the person?

P.S. I also know of teh two steps authentication and will enable it in the next couple of hours on her account