When do you call an Illegal pitch?

[AtlUmpSteve]

Originally Posted by BuggBob

The not illegal pitch camp said the pitch does not start until the hands separate, the pitcher could have corrected her error by stepping off the plate. But by me calling the pitch illegal she did not have that opportunity.

Bugg

I am in this camp. It is not yet an illegal pitch, because the pitcher can legally disengage prior to separating her hands, thus prior to starting the pitch. This is the one and only action that she can do to avoid the illegal pitch; once she separates, starting a pitch, it is THEN an illegal pitch.

I have been told that at least one ASA NUS member (WS) has said otherwise, but see no backing in the rule book, RS, manual, casebook, or official ruling from OKC.