You could have a look at the history in the browser and check if they connected to any sites if any have been connected to e-mail the owner of the site explain your predicament and see if they have a list of IPs for that day and time you may be able to get the IP that way.
Before you do that you'd need to check they actually got in to the laptop.
You didn't say what security you have on the laptop as you may have a firewall that saves IP's like mine and can check both in and outgoing there.
Another thing I'd do is check they didn't install anything on to the laptop, such as keyloggers, malware ect, and don't connect it to anything before you have scanned. Maybe this is overkill but it does not hurt to air on the side of caution.
I think also you can get tracking software now to install on your pc that has the ability to delete the HD remotely if such an incident occurs again and I think it tracks the Pc's location. Maybe one of the tech Geeks knows what its called as I can not remember.