PORTLAND — A Mexican national has admitted helping undocumented workers get fake identification cards.

Roman Garcia-Lopez, 56, of Portland pleaded guilty Wednesday in U.S. District Court to conspiracy to produce and transfer false identification documents.

He is scheduled to be sentenced in January.

Using the name Romeo Bartalon, Garcia-Lopez sold false permanent resident and Social Security cards to people in 2011 and 2012 in the Portland area who were in the U.S. illegally, according to the prosecution version of events to which he pleaded guilty.

With the help of a cooperating witness not identified in court documents, agents from Homeland Security Investigations made a controlled purchase of fake documents in May 2012 from Garcia-Lopez for $180. Individuals would provide biographical information to the defendant who would forward it, along with a photograph taken with his cellphone, to the person who made the documents.

The documents later would arrive via the U.S. Postal Service from the Atlanta, Ga., area, according to court documents. Information about Garcia-Lopez’s contact in Georgia is not included in documents filed in Maine.

Garcia-Lopez is facing additional federal charges related to his possession of false documents on March 11, 2013, when he was arrested by Portland police for operating without a license and failing to give a correct name. He has pleaded not guilty to one count each of employment verification fraud and Social Security fraud.

That case is pending in federal court in Portland. A hearing on a motion to suppress Garcia-Lopez’s statement to police has not been set.

Garcia-Lopez has been held without bail since his arrest in March.

He faces up to 15 years in federal prison and a fine of up to $250,000 for his involvement with the scheme to sell fake documents. If convicted on the other charges, he faces up to five years in prison and a fine of up to $250,000.