Guess who may be checking you out on Facebook, Wikipedia and MySpace?

The Department of Homeland Security and the FBI are poring over non-verifiable profiles on the Web to help decide who should be allowed into the country and who may pose a threat to national security.

Information is even being collected through Google searches, DHS and FBI sources confirmed to FOXNews.com.

Sources say that immigration officials vetting applicants for citizenship or asylum scan personal profiles, looking for telling pictures or information to help confirm marriages, verify background details and see with whom they're chatting online.

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Even U.S. citizens are having their Web profiles reviewed. People who buy one-way airline tickets, for example, are automatically flagged for security reasons, and authorities say a passenger’s name may be crosschecked against Facebook, YouTube or MySpace.

Remember those hunting pictures that you proudly posted online — the ones that show you holding a gun? If Homeland Security doesn't like what it sees, it could use them to ban you from stepping on American soil.

Charles H. Kuck, president of the American Immigration Lawyers Association, said millions of ordinary people check out their friends and other people's friends on Facebook and MySpace, so it shouldn't be surprising that the government does, too.

"We've known for years that immigration's been using these [sites] — Facebook, MySpace, going on Google, you name it — both at the ports of entry and beforehand, when [U.S. Citizenship and Immigration Services] is determining cases," said Kuck. "It's the information age and the folks at CSI and DHS are taking advantage of it."

But some critics say using these Web sites to gather information about individuals is unfair.

The problem, they say, is that the sites have no verification process. Wikipedia and Facebook can be edited by anyone with access to the Internet. Sites such as YouTube and MySpace have no content requirements, beyond those that filter offensive or objectionable material. And nearly all sites allow users to make up a profile in someone else's name. (Just see how many fake celebrity profiles there are out there.)

"When you have someone's personal freedom at stake, when you're getting into who's going to be allowed in the country, it's too important to rely on open source online sites that can't be trusted," said Jason Richards, a Florida attorney who has written about the use of Wikipedia. "It's a travesty."

Two weeks ago a federal appeals court ruled that the Department of Homeland Security should be disallowed from using Wikipedia as its sole source of information after agents consulted the online encyclopedia entry of a woman from Ethiopia who was seeking asylum.

Immigration officials questioned whether an Ethiopian travel document proved the woman's nationality. Agents presented a Wikipedia entry as evidence that the document didn't prove nationality. The judge agreed, but the 8th U.S. Circuit Court of Appeals threw out the decision, saying more information was needed.

As of yet, no legal precedent has been set for the use of other open source Web sites such as Facebook, but many experts say as long as DHS continues to use these sites, it is just a matter of time.

"We've gotten into culture of laziness. It's the easy way out when you go look up someone online, go to Google, Facebook, etc." Richards said. "It's a good starting point, it can take you places, but it can't be the end point."

Former U.S. Immigration and Naturalization Service Commissioner Doris Meissner said immigration officers are told to consult as wide a range of available sources as possible — Facebook and MySpace among them — and it is common knowledge that some sites carry more weight than others.

"At least with Wikipedia, there is ongoing updating and editing, and the updating may not be authoritative but it is an increasingly trusted source," Meissner said. "[MySpace and Facebook] are even less reliable sources," she said.

Officials are also trained to be cautious of applicants who set up fake Web sites or stage photos to improve their immigration status, Meissner said.

"You can never be sure if an attorney or a person is trying to approximate or copy circumstances or game the system," she said. "[DHS officials] might try to Google to get information, and follow those leads. But it would not seem — on the face of it — that it would not seem to be sufficient for determining something that is as significant- for the government as well as the individual."

Kuck said more needs to be done to train federal authorities to use some common sense in their Web investigations. "Someone writes something about you that says, 'Hey, you're a terrorist,' well, that's serious," Kuck said. "But other times one of the main problems is they don't use the rule of reason. It's a culture of no."

Ultimately, he warned, when it comes to personal information, it’s up to the individual to show good judgment when posting anything online.

"It's shocking what's out there about you on the Internet — what you wrote on that Facebook page, MySpace page back in high school that you don't use anymore. Anything you've ever written and anything anyone's ever written about you, it's all still there," said Kuck.

For now, experts say that until Facebook meets Wikipedia's fate in court, how DHS officials react to that photo of you smiling, dressed in local garb and brandishing a spear while on vacation is up to them, and you'll be judged accordingly.

"You hate to tell people, "You should go online and Google yourself." But before you go and get on that plane, well, maybe you should," Kuck said.

Now might be a good time to change that profile picture.