squirrel in the attic - how to get rid of?

[George P.]

Anyone knows how to get rid of the squirrel who sneaks into the attic early in the morning and wakes everyone up with her stupid scratching?
I got up the attic area but didn't find any holes whatsoever, although half of the attic is not inspectable due to space limitations.

Any suggestions (humane as well as not) are welcome - please throw your ideas, but don't make fun. This creature needs to leave.