I just tried to log on to my blockchain wallet from a different country and I had to manually verify via email the logon attempt. So it seems unlikely that someone outside of your vicinity logged into your account without you knowing. Did you have the logging options within blockchain activated? If not then you're not going to be able to tell who did it.
Even so, I don't know if storing 9.67 BTC on a web based wallet is such a great idea.
TBH it is pretty irresponsible of these companies to not restrict outgoing transactions without verification via email at the very least.
It is not by location, it is by browser (they check for a cookie on your browser). They will not however allow you to authorize a login attempt by someone outside of a certain IP address range. Even so, I don't know if storing 9.67 BTC on a web based wallet is such a great idea.
TBH it is pretty irresponsible of these companies to not restrict outgoing transactions without verification via email at the very least.
The most likely scenario is that the OP's backups were somehow compromised and/or has some kind of malware on his computer that would automatically create/push a transaction of all bitcoin stored on his computer
I also have a blockchain wallet but I've never stored more than 0.5 btc on it. I advise you to use a paper wallet for large amounts of btc next time. 
