Board Thread:Questions and Answers/@comment-24.4.122.254-20130629204233/@comment-1405841-20130707040950

Over at DexterDaily (a site dedicated to Dexter related news), apparently Vogel only knew Harry. Harry, when discovering that his son had something "wrong with him", sought out therapy from the only person who would listen (and probably not judge and/or make a fuss about it): Evelyn Vogel. She helped Harry through it and probably influenced him into creating the Code. That's how she knows all about Dexter and why she has those drawings he made, it's likely Harry saw these drawings and knew with everything else his son was dealing with he needed answers and a way to deal with it.

We'll find out though, maybe tomorrow even.