Scop (D) was one of several individuals indicted for mail and securities fraud in connection with the trading of stock in a car dealership. D was involved in a scheme to inflate the price of the stock, whereby the parties fixed the trading by providing buyer, seller, and price in every transaction. The government's case against D rested in part on the testimony of Whitten, an SEC investigator. Whitten testified solely on the basis of evidence introduced at trial. Over D's objection, he was permitted to answer a question concerning his opinion as to whether there was a scheme to defraud investor. In doing so, Whitten repeatedly used terms contained in the statute under which D was being prosecuted such as 'active participants' and 'material participants' in the manipulation of EAC stock. D was convicted and appealed claiming that the admission of the expert testimony was improper because it involved legal conclusions which are not within the scope of Rule 704.