I don't think the CEO is going to answer an anon. email.
Take the bull by the horns and go talk to him/her.
Then, let the cards fall where they may. Even if she doesn't get fired, they will be on to her.
You know, however, your h won't be able to use the CEO as a reference if you out them.
FYI I did call the HR manager at my XWH company, but he sorta blew me off. He said unless it affected his work he couldn't do anything.
However, your situation is different.
Also, do you have proof to give the CEO?
I say go for it!