 -- Officials overseeing a federal program that offers an immigration short-cut to wealthy foreign investors have ignored pointed warnings from federal agents and approved visas for some immigrants suspected of having committed fraud, money laundering, and even one applicant with alleged ties to a child porn website, an ABC News investigation has found. The shortcomings prompted concerns within the Department of Homeland Security that the boutique immigration program would be exploited by terrorists, according to internal documents obtained by ABC News.

“It is shocking,” said Sen. Charles Grassley, an Iowa Republican. “Particularly when you have F.B.I. and other law enforcement agencies that are saying national security could be compromised or is being compromised -- that's enough for us to be concerned.”

Five different Homeland Security whistleblowers spoke with ABC News about a range of cases where visas were approved despite numerous red flags. They said objections were often ignored because the immigration program is so popular within the Obama Administration and with members of Congress from both parties. Known as the EB-5 visa program, foreigners who are willing to invest $500,000 in an American business can jump to the front of the line and obtain legal status to live in the U.S. for two years. If the investment is shown to create at least 10 jobs, the investors can receive a “Green Card” -- permanent residency.

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Following publication of this report, Department of Homeland Security Secretary Jeh Johnson said today he is “aware of the concerns” raised by ABC News “centering around security” and said the DHS “continually evaluate[s] whether more security should be provided for the program.”

Some immigration groups have criticized the program as “nothing more than selling Green Cards.” Brent Wilkes, the executive director of the League of United Latin American Citizens, one of the largest Hispanic civil rights groups in the U.S. said it “short circuits” the immigration process, allowing foreign nationals “with enough cash” to leap ahead of legitimate applicants who lack the means.

Supporters call the program a “win-win” because as the investors accelerate through the immigration process, their overseas money helps spur job-creating projects in the U.S.

“The American worker [is] able to get to work thanks to the capital investment coming through the program,” said Peter Joseph, the executive director of the Association to Invest in the U.S.A., a Washington, D.C. group that has advocated for the little-known immigration program.

But an ABC News investigation found that in addition to reaching wealthy foreign investors, the program has become a magnet for those seeking to sidestep the scrutiny of the traditional immigration process. In one case, immigration officials pushed through a visa application from Chinese investor in a Las Vegas hotel project despite an internal review that found the investor had previously been turned back at the border, and much of his visa application had likely been fabricated, immigration records show.

A Feb. 1, 2013 Homeland Security internal review obtained by ABC News also lays out in stark detail the breadth of the troubles afflicting some of the roughly 600 so-called regional centers -- private sector entities certified by Homeland Security to recruit foreign investors for specific business ventures that will qualify for EB-5 visas. The document summarizes 41 investigations, some open and some now closed, into allegations ranging from espionage to fraud to drug trafficking involving investors in various EB-5 investment projects.

One regional center, run by an Iranian-born businessman living in Beverly Hills was approved to raise roughly $25 million in investment money from foreign sources even when one of his businesses was being raided by agents. Federal officials told ABC News the businessman is suspected of allegedly smuggling banned items to Iran.

Another regional center raised money from Chinese investors to finance the construction of federal buildings, including an FBI headquarters building in San Diego, raising what one internal document called “national security concerns” that “pertain to Chinese investors having visibility to FBI blueprints/information.”

DHS spokesman Peter Boogaard did not respond to a request for updated figures. But he and other Homeland Security officials have defended the program –- acknowledging past problems but arguing that improvements have drastically reduced the cause for concern.

Late Monday night, DHS released a statement in which it said the immigration agency “only has the authority to terminate a regional center if there is evidence the center is no longer promoting economic growth -– not on the basis of national security concerns.”

“This lack of discretion limits the ability of the Director or the Secretary to terminate a regional center in the event of suspected or even proven criminal activity,” the statement says, adding that the administration sought additional leeway from Congress to act on security concerns but did not receive it.

Advocates for the program also acknowledged the visa program had suffered from occasional failures. But they touted the numerous successful projects that have been financed through this form of foreign investment, and credit it for spurring job growth through some of the toughest years of the shaky economy.

“I don't think we should let a few anecdotes cast a cloud over an entire industry,” Joseph said.

Joseph noted the program is now so popular that the 10,000 visas allotted in 2014 for EB-5 investors were claimed in a matter of months, and he is lobbying for its expansion. The money has paid for popular projects -- a Brooklyn basketball arena, a California winery, a Vermont ski lodge, even a Hollywood movie studio – that have supported an estimated 42,000 jobs.

“It's a win for the investor, who's seeking to get an immigration benefit, along with a return on their investment, along with the American worker who's able to get to work, thanks to the capital investment coming through the program,” Joseph said.

In recent years, as the program has grown dramatically in popularity, it has sparked controversy.

In 2013, then-Virginia gubernatorial candidate Terry McAuliffe was accused by political opponents of trying to prod federal officials to approve visas for investors in an electric vehicle start-up venture he ran. He denied that he sought undue influence. In 2014, questions about an EB-5 investment scheme in South Dakota became grist for political ads targeting then-U.S. Senate candidate Mike Rounds, who was attacked for his role in oversight of investment projects while he was governor. Rounds called the attacks political and "inaccurate" and "defamatory."

Questions about the SLS Hotel project in Las Vegas first gained attention when an article in The Washington Times revealed that Homeland Security expedited the processing of investor visas after Nevada Sen. Harry Reid (D) and his staff began prodding the department to move faster. Reid aides said their push to eliminate longstanding bureaucratic hurdles with the program and was aimed at creating local jobs.

But in a series of interviews, Homeland Security whistleblowers who spoke with ABC News on the condition they not be identified said their greatest concern was that political pressure to expedite the review process has led officials to grant visas to applicants who had significant red flags in their backgrounds.

When the SLS Hotel chain sought to fund construction of a hotel on the Las Vegas strip using foreign investors, Reid and his aides urged immigration officials to speed up their review of the visa applicants, internal emails show. Each visa applicant approval meant another $500,000 could flow into the construction budget, and the developers were anticipating as much as $200 million from foreign investors.

Michael Vannozzi, then a top aide to the senator, wrote to say that a failure by immigration officials to push through approvals could cause the project’s major investor, JP Morgan Chase, to back out. Emails show Reid personally appealed to the then-head of USCIS, Alijandro N. Mayorkas, to give the matter his attention. Mayorkas, who has since been promoted to deputy secretary, responded to the request by saying he would take “a fresh look” at the issue.

Shortly after the agency reversed course and sped up the processing of SLS Hotel investor applications, a career immigration official wrote in a Feb. 3, 2013 email that the decision had been “shoved down our throats” after Mayorkas and his senior advisor had “refused to listen to any operational concerns about expedites, including fraud and national security.”

ABC News obtained copies of background reports prepared by government fraud detection specialists about several of the SLS Hotel investors. The investigators raised questions about those applicants’ background –- most of them Chinese applicants who could not sufficiently document the source of their $500,000 investment. Applicants must present proof the money is not the product of illegal activity, or funneled to them by a government entity to help get a spy into the U.S.

In one case, a fraud investigator found bank documents “with eraser marks” and touched up with whiteout. In another, employer information the investor produced proved to be false. In a particularly glaring case, investigators found an applicant who had previously been refused entry into the U.S., and who submitted his application “with forged and fraudulent documents.”

“It is suspected that entry into the U.S. was to knowingly enter into a marriage fraud scheme,” the report states. The determination of this review: “Fraud found.”

Subsequent records from the applicant processing system, obtained by ABC News, show that an “intent to deny” notice was sent to the investor in February of 2014. But the decision was reversed in May. On May 27, the applicant’s visa was approved.

Inside the immigration agency, whistleblowers said, there were serious concerns surrounding another applicant who sought to invest in the SLS Hotel project. In 2013, the applicant was flagged by FBI agents who had been reviewing EB-5 cases. “Please really look” at the applicant, the FBI agent urged in one email. Immigration officials conducting background checks on the man found that his wife was a possible match for a woman who had received payments from people accessing a child pornography web site.

Investigators found “unusual wire transfers” and “suspicious financial activities” that included “a front company whose real purpose is to launder the investor’s capital” and “appear to be an effort to obscure” the source of his funds. Records show that customs officials had, at least twice, denied him entry into the U.S.. But documents obtained by ABC News show that his approval notice was sent on Jan. 29, 2014.

Ron Klasko, one of nation’s top EB-5/immigration lawyers, represents SLS Las Vegas and helped handle the visa applications for the hotel project. He said in an interview that no applicant can be rejected based on rumors or suspicions. There must be “either a conviction or a reason to believe that he’s engaged in criminal activity,” he said. He said that every SLS Hotel investor was subjected to layers of scrutiny before even being submitted for consideration by immigration officials.

“There were some investors where I reviewed it and we were not comfortable,” Klasko told ABC News. Even before the applications came to him, he said an agent working in the investor’s home country went through “a two to three month process to document how the investor gets his money... No one wants to be in the business of refunding the money.”

Klasko said that not all the applications were approved without questions. “In some there was a request for evidence. It came back to us. But as far as I know, [eventually] 100 percent of the investors were approved,” he said.

The SLS Hotel project opened to great fanfare last year, with an enormous fireworks display over the city meant to celebrate this sign of economic rebirth. Today, it is heralded as one of the EB-5 program’s most notable achievements, including by Senator Reid.

“Senator Reid is proud to have successfully fought for a project that creates 8,600 Nevada jobs,” Reid’s spokesman wrote in an email responding to questions from ABC News. Reid’s statement notes that his office advocated for the project to receive immediate attention, and nothing more. “It is worth noting that Senator Reid can't affect the ultimate outcome of these petitions,” he said. “Expediting the review of petitions has no bearing on whether they are adjudicated favorably or not. It just moves petitions to the front of the line.”