PHOENIX -- A state prison guard has been indicted in a Phoenix-based fraud scheme that charged as much as $7,500 for fake immigration documents and victimized more than 500 people, authorities said Tuesday.

Victoria O. Romero, 36, of Buckeye, has been charged with fraud, conspiracy and money laundering in the case, said Arizona Attorney General Terry Goddard.

Authorities said the scheme attracted victims across the country with the promise of obtaining legitimate "green cards."

In an effort to show their legitimacy, the defendants put each victim through an application process that included having their fingerprints taken. Victims actually received phony cards or no cards, authorities said.

The indictment alleges that Romero, a guard at the State Prison in Perryville and now on administrative leave from the Arizona Department of Corrections, took some of the victims' fingerprints and often was in uniform when she performed the task.

Romero also allegedly used her credit card, or allowed her credit card to be used, to purchase a fingerprint stand and 300 FBI fingerprint cards for use in this fraud scheme, authorities said.

Romero is scheduled to be arraigned June 7 in Maricopa County Superior Court.

If convicted, prosecutors said she faces a maximum sentence of 20 years in prison and a $180,000 fine.

Carmen Tolle, 42, of Phoenix, was the leader of the scheme and pleaded guilty to fraud and theft with a prior conviction, authorities said.

Tolle was sentenced earlier this month to 7 1/2 years in prison and five years probation and was ordered to pay $75,690 in restitution.

The investigation, which began in April 2005 and was conducted by the Arizona Financial Crimes Task Force, found that many of the victims traveled from as far as New York City and Miami to receive the fake documents.