Two brothers who own three popular Mexican restaurants in Maine pleaded guilty Monday to charges related to hiring undocumented workers, rather than face what would be their second trial.

Guillermo Fuentes, 38, of Westbrook and Hector Fuentes, 40, of Waterville were convicted in U.S. District Court in Portland in March 2013 but were granted a new trial because one of the jurors referred to them with a racial slur.

With their second trial tentatively set for October, they chose to waive the indictment process and plead guilty to knowingly hiring 10 or more undocumented workers in a one-year period and making false statements to government agents.

Each brother faces as much as five years in federal prison and a fine of as much as $250,000 on each of the charges. Their sentencing date was not immediately available.

Judge D. Brock Hornby issued an order last summer granting them a new trial after learning that the juror made the slur to a man at the Eagles Club in Portland on March 9, 2013, after the second of seven days of testimony in the trial, according to court documents.

The man at the club who heard the slur was on probation and reported the conversation to his probation officer. He said the juror told him that he wasn’t supposed to be talking about the case but that the defendants were guilty anyway, and referred to them with a racial slur, according to the judge’s order.

The probation officer did not learn the juror’s name until April.

The judge said in his order that he interviewed the man who was on probation and the juror last year. He said the juror first denied making the slur, but ultimately admitted to it.

Hornby said in his order that the juror’s comment raised two important concerns, “that at that early stage of the trial this juror had already made up his mind that the defendants were guilty, and that ethnic stereotyping affected his judgment.”

The U.S. Attorney’s Office says that from 2006 to 2011 the brothers helped undocumented workers at the Fajita Grill in Westbrook, the Cancun Mexican Restaurant in Waterville and the Cancun Mexican Restaurant II in Biddeford get green cards and Social Security cards.

The Fajita Grill became popular in Westbrook soon after it opened, known for its fast service, lively wait staff and super-sized margaritas.

Several workers testified during the trial that they worked six or seven days a week, from 9 a.m. to 10 p.m., with only one two-hour break. Kitchen workers said they were paid in cash. Waiters and waitresses weren’t paid but kept their tips.

The Department of Homeland Security’s investigation into employment practices at the Fajita Grill was prompted by a tip from Westbrook police Capt. Tom Roth, court documents say.

The documents say Roth told the federal agency that in routine traffic stops in April 2008, Westbrook officers encountered Hispanic men who appeared to work at the Fajita Grill, claimed to be from Mexico and could not provide any U.S. identification.

James Bell, a special agent with the Department of Homeland Security, interviewed four workers, all of whom had worked for the Fuentes brothers at a Mexican restaurant in Atlanta called El Potrillo.

They told Bell that they moved in 2006 with about a dozen other employees to work for the brothers at the Fajita Grill, and later at one or both of the Cancun restaurants.

Bell said they were paid $300 to $500 weekly in cash for working about 60 hours.

Three of the people who were interviewed reportedly told Bell that when they arrived in Maine, they and seven or eight other undocumented workers temporarily lived rent-free in the basement of the Fajita Grill.