Investigators of the Madoff Ponzi are looking at possible offshore accounts that may have been used as tax havens for wealthy investors.

"While the inquiries into the role of offshore funds in the scheme
are at an early stage, it is hardly surprising that such funds are
coming under scrutiny. Offshore entities played key roles at
Bayou Management, a Connecticut hedge fund that collapsed in scandal in
2005, as well as at Enron, which used nearly 900 offshore entities, mostly in the Cayman Islands, to conceal bogus trades and accounting fraud."

 "At least a dozen offshore entities were involved with Mr. Madoff’s
firm, according to several regulatory filings. They include funds
linked to the Fairfield Greenwich Group, a fund of funds that lost $7.4
billion of its investors’ money after entrusting it to Mr. Madoff".