To many people, the Cayman Islands represent little more than a location for a sun-soaked Caribbean getaway.
But to Max Baucus, a US senator, they are where millions of unpaid US tax dollars could be stashed and he claims to have a photograph to prove it.
At a Senate hearing into offshore tax havens last week, the Montana Democrat held up the image of a five-storey building in the Caymans, enlarged for the benefit of the TV cameras present.
"Over 12,000 corporations are lodged in there and the suspicion is that they are shell [companies] whose sole purpose is to evade US taxes," he thundered.
He then turned to an official testifying from the Government Accountability Office, the investigative arm of Congress. "I'm going to ask you to go down there. I want you to root around and come back and tell us what you can find."
Offshore tax havens are once again in the sights of Congress. Alarmed at the growth of the so-called "tax gap" the amount by which US taxpayers are estimated to be underpaying their taxes and under-reporting their income some lawmakers are pointing the finger towards the Caribbean and other offshore tax havens.
They suspect that US citizens are using bank secrecy laws and the ability to channel income through tax-free offshore vehicles to evade reporting income to the Internal Revenue Service.
Jeffrey Owens, director of the centre for tax policy and administration at the Organisation for Economic Co-operation and Development, said an increased reliance by investors on shell companies with opaque structures based offshore could make it hard for domestic tax authorities to track income.
Asked how big the problem was, he confessed to senators: "We just don't know."
Yet such congressional concern comes as offshore financial centres have been cleaning up their acts, narrowing the gap between offshore and the developed jurisdictions including the US against which they are often unfavourably compared.
A report out last month commissioned on behalf of the International Trade and Investment Organisation, a group of small countries with international finance centres, pointed out that many offshore centres have better standards than larger onshore ones.
Alden McNee McLaughlin, the Caymans minister for international financial services policy, recently said the islands "deeply resent" the idea that "because we are not located onshore we are illegitimate".
Offshore financial centres have improved their standards as a result of an OECD harmful tax competition initiative, launched in 1996.
In 2000, it published a "blacklist" of 35 tax-haven countries, which prompted offshore centres to make commitments to remove harmful tax practices, improve transparency and exchange information.
The British Virgin Islands recently abolished its system of bearer shares, which conceal the identity of the beneficial owner in a company. Yet many US states, including Delaware, do not require companies to show such information.
Robert Briant, a BVI-based partner at Conyers Dill & Pearman, the law firm, questions whether the use of offshore financial centres for tax evasion is increasing. "What is the basis for that given the amount of information that's provided for an offshore company as opposed to an onshore company? It's a disconnect."
Most experts agree the best way to tackle the US tax gap is to improve information-sharing between developed countries and those offering tax-free services.
That has become more urgent with the emergence of developed countries marketing themselves as tax-efficient such as Singapore and Malaysia.
The US has implemented "tax information exchange agreements" with tax-free jurisdictions since the 1980s.
However Reuven Avi-Yonah, a tax expert at the University if Michigan, points out most of them are of "limited value in closing the overall tax gap" because they are limited to criminal matters, which form only a "very small" part of overall tax collection issues.
The agreements sometimes require the subject matter to be criminal in both the US and the tax haven, "which would never be the case for pure tax evasion".
Few observers expect congressional scrutiny to result in legislative action. But Mr Avi-Yonah recommends that the US should persuade tax havens to enter into new agreements along the lines of a recently-unveiled OECD model that tackles many of these problems.
"Fundamentally the whole tax evasion question could be addressed if we co-operated with all the other developing countries," he says.