Who cares about what is keeping you... you just want to empty the trash and move on with your life.
A good tip to do just that, is to use the "Secure Empty Trash" option in the finder File menu options. This will do just that, empty the trash - without having to do anything like command line stuff, open a 3rd party app like this one, etc...
Keep in mind, this won't work for stuff that is truly still running as a root process, and it will take awhile for larger files trying to be trashed since it is writing 1s and 0s over that data...
But for a quick tip, it works nicely and you won't have to worry about whats keeping me or anyone else for that matter.
Cheers!