Get breaking news alerts and special reports. The news and stories that matter, delivered weekday mornings.

The community space used by the San Diego nonprofit Border Angels bustles during free advice sessions. In recent weeks, as many as 40 people have shown up for a single event in need of immigration help — up from the typical two or three, said founder Enrique Morones.

Now, people are pouring in with similar stories of desperation, he added: Someone offered to "fix" their immigration documents for money. They paid anywhere from $500 to $5,000. Then the person inexplicably vanished.

"In times of confusion like right now, there are people who see it as the perfect time to prey on victims," Morones told NBC News.

Defrauding the undocumented has endured over the decades, but the uncertainty surrounding the Trump administration's immigration policies has government agencies and advocacy groups worried that more people are getting swindled — or seeking out situations that are unscrupulous.

"Never have we had the situation we do now because of this Trump effect," Morones said.

In addition, the legal wrangling over President Donald Trump's revised travel ban, which affects refugees and certain visitors from six Muslim-majority countries, has only added to the confusion and opened up the potential for fraud of visas, green cards and other documents, immigration advocates warn.

Scammers themselves are becoming shrewder.

With Trump's policies encouraging Immigration and Customs Enforcement to carry out deportation raids and frowning upon so-called "sanctuary cities," New York officials have reported complaints of men posing as agents and wearing ICE-emblazoned jackets to shake down people for money.

New York Attorney General Eric Schneiderman called the scheme "unconscionable."

Related: Cinco de Mayo-Related Celebration Canceled, Some Fear ICE Raids

ICE says agents will never ask for money, much less threaten detainment or deportation because they weren't paid.

The Morning Rundown Get a head start on the morning's top stories. This site is protected by recaptcha

Officials in Arizona also reported a similar telephone scheme perpetrated by fake federal immigration officers.

In Utah, the newly formed Refugee Justice League — made up of about 80 pro bono attorneys — is on alert for shady situations. The group has been hosting training events this month to inform refugees of their rights.

Attendees look on during a training event to make sure refugees and immigrants understand their rights under President Donald Trump's travel ban and refugee program suspension in Salt Lake City on March 21, 2017. Rick Bowmer / AP

"The refugee area is ripe for someone who wants to take advantage," said attorney James McConkie.

McConkie said he has heard stories about other attorneys who take money from refugees for paperwork when it should have been free. Seeking help isn't an option for some victims.

"They're scared to death of police, and they don't want to be themselves accused of wrongdoing," McConkie said. "There's still this cultural divide with how [refugees] perceive law enforcement."

Related: Here’s a Place in Trump’s America Where Refugees Are Welcomed

The Federal Trade Commission received roughly 1,100 complaints related to immigration services in fiscal year 2016. But since not everyone is willing to report bad experiences, instances of questionable motives or worse, criminal immigration fraud, can often fall through the cracks.

Arrests and convictions for document fraud, which relates to altering or counterfeiting papers, and benefit fraud, which relates to misrepresenting information on a petition, spiked during the George W. Bush administration. The numbers rose again during part of the Obama administration before falling in fiscal years 2014 to 2016, according to ICE.

Erik Ortiz

Experts say the lower number of arrests could be attributed to the shifting immigration policy under President Barack Obama, who backed off deporting undocumented immigrants who have committed no crimes or came to the U.S. as children. The lower fraud rates, experts add, could also be affected by certain types of illegal immigration dropping at the Mexican border in recent years, while the use of biometric and tamper-resistant documents have made document fraud more difficult.

Kevin Johnson, dean of the UC Davis School of Law, said he wouldn't be surprised to see the number of arrests eventually jump again "with this administration encouraging implicitly and explicitly reports of fraud."

RELATED: AG Sessions Threatens 'Sanctuary Cities': Mayors Fight Back

Former New York attorney Earl Seth David also believes the level of deception and fraud is sure to climb as the undocumented are ensnared — some out of their own volition. David would know: He was arrested in 2011 in what federal prosecutors say was perhaps the largest visa fraud mill in U.S. history.

Then-U.S. Attorney Preet Bharara said at the time that David "abused his attorney’s license to exploit his alien clients who were seeking the American dream."

David, however, told NBC News recently that he felt a sense of duty out of his Jewish faith to help those who only wanted a better life and were desperate enough to risk everything to stay in the United States.

"Never have we had the situation we do now because of this Trump effect."

From 1996 until 2009, David's Manhattan firm cranked out tens of thousands of immigration applications using phony pay stubs and tax returns for each client, prosecutors said. In addition, the firm doctored employment recommendation letters by setting up shell companies that told the U.S. government they would sponsor David's clients for employment.

Those applications were passed on to immigration officials to obtain a "legal" green card. For years, the government failed to properly vet the paperwork.

Immigrants from South America, Europe and Africa all sought David out. They were willing to pay — some as much as $30,000.

The government also collected money from each application — about $1,500, according to David — and unwittingly approved the documents before David's firm was finally shut down.

David fled to Canada but was extradited before pleading guilty in 2012 along with other co-conspirators who worked for him. He spent more than three years in prison before he was released in 2015 to a halfway house and then home confinement. He no longer practices law and remains adamant that the result was worth it: His clients didn't have to surrender their green cards, and many were ultimately permitted to remain in America.

David said the immigration system must still be improved — or the unlawful acts will only continue. "I did what I did because I really thought I was helping people," he said.