I will say that I have business associates that knew traders who did legitimate trading within Stanford's network, which extended beyond just the offshore CDs.
They saw reason for caution and had no interest in investing with Stanford, despite the attractive terms. A big reason being the use of the offshore bank, despite the SEC supervision onshore. Which indeed proved to be a major risk of fraud.
Their caution was proved justified, and this was several years before the high interest rates became suspicious due to the changing market.