A federal grand jury in Houston has indicted two women who investigators say took in large profits by running a phony marriage scheme as a way for immigrants to gain legal status. Authorities worry that such criminal operations could help terrorists gain access to US.

In all, the indictment charges that 210 bogus marriages took place during the past two years as a way to help foreign nationals obtain permanent resident visas to live and work here. U.S. Attorney Michael Shelby says such conspiracies to violate immigration law are a potential threat to American security.

"Never before in the history of this nation has the enforcement of our federal immigration laws been as important to our national security as they are today, and we cannot, and we will not, allow people to blatantly circumvent, to blatantly disregard those laws for personal profit," he said.

The U.S. Attorney says there is no evidence that any of the people who benefited from this conspiracy were in any way linked to terrorism, but that such operations could be exploited by terrorists. In this case, he says the immigrants were only interested in the legal residence document, known informally as the "green card."

"That is the holy grail that is sought by people who want to immigrate to the United States, because that is the card that allows them what they are really after, which is employment in this country," he said.

Named in the indictment are two Texas women, Aminata Smith of Houston and Emma Guyton of Bryan.

They are charged with running a for-profit sham marriage operation with as many as 60 U.S. citizens who were each paid between $150 and $500 to marry a foreign national. The pair charged the foreigners between $1,500 and $5,000 for a bogus marriage.

The foreign nationals, most of whom came from Africa or the Middle East, entered the United States on tourist visas or student visas and then applied for permanent residence after marriage to a U.S. citizen.

U.S. immigration procedures are expedited for foreigners married to U.S. citizens. But in this case officials became suspicious after an investigation revealed several cases of the same citizens being married multiple times with no record of divorce.

The grand jury also indicted 36 of the U.S. citizens involved in the scheme. Of those, 14 are in custody and the others are being sought. The government is also seeking 36 foreign nationals as material witnesses and is continuing an investigation that may lead to the indictment of others in the near future