Question about grep expressions

I would like to write a grep expression which includes keyword1, any character up to 80 characters long, keyword2, exclude keyword3. This is my attempt but it doesn't seem to work.

Grep expression in EnCase e.g. Roger .{80,80} is undergoing [^tremendous].{10,10}investigation

I am searching for a string given to me by my client "Roger bla bla bla bla bla is undergoing an investigation". And I'm trying to exclude hundreds of false positives such as Roger Clemens ex-pitcher NY Giants is undergoing tremendous bla". I created a test document with both sentences from above and neither seem to hit. Can someone give me a hand?
BTW - I'm not really on a case involving a Roger. 😉

Thanks,