A beneficiary was banished. Does he still inherit?

This letter from a reader is one of those questions that reminds me of why I blog in the first place. It reminds me of how much misinformation is out there, and how tough it can be for people to know what is "legal" and what is not. Here is the question:

"What if there is no will and someone dies leaving two siblings the estate? One sibling was banished from the property - what are his rights