Source of Money is one of the most important elements of a US Treaty Investor's visa. Based on Visa Qualification Requirements, an applicant must know the source of money before he/she would apply for the Treaty Visa.
Establishment of the source of money is not always an easy matter. Some countries have a different financial system than USA. This makes it difficult to adequately show where the money has come from.
Sometimes we could prove the way of generating the money, but we can't trace the available funds to the funds generated for the lack of proper documentation.
Treaty Trader & Investor Visas (E2) need a patient legal counsel, not to mention, client's full cooperation is an important key to success.