This NY Times article reports on the increasing difficulty of secretly stashing ill-gotten money in Swiss bank accounts. The article notes as follows:

According to a report in March from the Paris-based Financial Action Task Force on Money Laundering, which is supported by 32 countries, only seven jurisdictions – the Cook Islands, Guatemala, Indonesia, Myanmar, Nauru, Nigeria and the Philippines – now qualify as “non-cooperative” in international efforts to block the flow of illicit funds.
Less than four years ago, the list comprised 15 countries, including many in the Caribbean, like the Cayman Islands, that have now been removed. . .
Not surprisingly, Switzerland has no wish to be associated with this list of shame, and its bankers say they have been tightening their controls since 1977.
That does not alter the fact that Switzerland’s bank secrecy laws, dating to 1934, impose far fewer obligations to report customers’ affairs than laws elsewhere.
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But there is a counterimage that resurfaced in the 1990’s, when Swiss banks were discovered to have denied survivors access to funds deposited by Holocaust victims. The Swiss National Bank, moreover, was obliged to acknowledge that it had accepted deposits of Nazi gold during World War II.
More than anything, the disclosures undermined Swiss respectability and persuaded the bankers that their image needed a makeover to protect an industry that employs 110,000 people and accounts for 11 percent of the country’s economic output.
Indeed, as the enforcement of regulations on illicit money has tightened, Swiss banks have become more cooperative with investigators, he said. Since Sept. 11, 2001, for example, Swiss authorities have frozen $26 million in 82 accounts said to be linked to Al Qaeda or the Taliban . . .

In addition to the foregoing, the Swiss banking bar is a remarkably small and close knit group. If clear proof exists that the Swiss banking system is being used to facilitate a criminal purpose, then, in my experience, members of the Swiss banking bar have been quite helpful in facilitating discovery of information relating to the funds and accounts in question.