Hi, I'm Michaele. I'm your security headache tonight

The story behind the pair of White House gatecrashers has just got even stranger

He's supposed to be the most protected man on the planet, living in a building described by one of his predecessors as "the world's finest prison." Now a red-faced and furious US Secret Service is trying to explain how a pair of on-the-make Virginia socialites managed to gatecrash a White House state dinner and shake hands with President Barack Obama in person.

For ordinary mortals, even with the proper clearance, getting into the White House is an obstacle course. But last Tuesday night Tareq and Michaele Salahi managed it without an invitation and, seemingly, without breaking sweat. The next day their Facebook site was already featuring photos of themselves at the event to honour the Indian prime minister, Manmohan Singh.

Then, late on the Friday night of the long Thanksgiving, a sheepish White House confirmed the Salahis had made it all the way, issuing a photo of them in the official receiving line, a smiling Michaele, clad in a red sari, grasping Obama's proffered right hand in both of hers. Now, all Washington is trying to work out how they did it. The answer seems simple. It was a mistake that shouldn't occur even at a routine airport gate, let alone the White House. No one bothered to check their identity against the guest list.

The agency was "deeply concerned and embarrassed," a Secret Service spokesman said. "Although these individuals went through magnometers and other levels of screening, they should have been prohibited from entering the event entirely. That failing is ours." But that grovelling apology may only make matters worse. Peter King, a New York Republican, is demanding a full Congressional investigation, while another lawmaker complained that while the Salahis had gone through metal detectors, "that wouldn't have stopped them bringing in anthrax spores or picking up a knife from the table".

Nor are the couple likely to have heard the last of their caper – mounted, it seems, to boost their chances of featuring in an upcoming reality TV show entitled The Real Housewives of DC. Cameras from Bravo, the channel which is considering whether to choose the Salahis for the show, followed them to the White House.

Disbelieving that so elementary a security slip-up was possible, some gossip websites have speculated that the Salahis, polo enthusiasts who have had social contacts with Indian officials here, had been put on a special guest list for last Tuesday. But this was flatly denied by both the Indian Embassy and the White House.

Instead, they could find themselves facing criminal charges. It is not clear whether gatecrashing is a criminal offence. But if they lied about their identity they could be in trouble: federal law states that it is a crime to give deliberately false statements on matters under government jurisdiction.

And that may not be the end of the couple's problems. In 2002, they celebrated what they modestly described as "the wedding of the century" at St Matthew's Cathedral here. They have had themselves photographed hobnobbing with Oprah Winfrey, and with the Prince of Wales at a polo meet. But their finances are shaky. The family winery in Virginia filed for bankruptcy this year, and they are reportedly behind on payments on their opulent home in the foothills of the Appalachians.