Raul Villarreal was long a public face of the Border Patrol, frequently appearing on television news as an agency spokesman and acting as a dangerous human smuggler in a public service announcement intended to warn Mexicans about the pitfalls of entering the United States illegally.

Prosecutors contend now that he knew the smuggler’s role well because he really was one.

Raul and his older brother and fellow former agent, Fidel, are accused of smuggling hundreds of migrants in Border Patrol vehicles. Federal prosecutors say the brothers were tipped off that they were under investigation in June 2006, prompting them to flee to Mexico.

Shortly after settling in Tijuana, a district police commander in the Mexican border city who allegedly shuttled the Villarreals’ customers in squad cars was killed in a hail of about 200 bullets. The brothers were arrested in Tijuana in October 2008 — more than two years after abruptly quitting the Border Patrol — and extradited to the United States to face charges of human smuggling, witness tampering and bribery.

The case, which goes to trial next month in San Diego, is one of the highest-profile corruption cases involving the Border Patrol since it went on a hiring spree during the past decade. The brothers, now in their early 40s, have pleaded not guilty to all counts.

The Border Patrol has suffered a string of such embarrassments since doubling its size over the past seven years to more than 21,000 agents. Its national strategy released last month emphasizes that even one misguided agent is unacceptable and outlines steps to combat corruption.

Criminal indictments against employees of Customs and Border Protection — which oversees Border Patrol agents and other border security officials — have increased each of the past four years to 60 in fiscal 2011, according to the Department of Homeland Security inspector general. There have been 232 indictments from October 2007 through April 2012.

The Villarreal case is unusual for the level of detail disclosed in recent pretrial briefings.

The family came to the United States from the central Mexican state of Jalisco in 1984, when the brothers were teenagers. Raul knew no English as a 14-year-old but quickly became fluent. He volunteered to read to children at libraries and collected food for the homeless, joining the Border Patrol in 1995 after earning a bachelor’s degree in criminal justice from San Diego State University.

Raul “pursued and achieved what is known to be the American Dream,” wrote David Nick, his attorney.

Fidel excelled as a student, got police training at community college, studied aviation at National University and joined the Border Patrol in 1998. His family says he had a habit of calling police to report graffiti in the neighborhood.

As adults, the Villarreal brothers lived with their parents and siblings at a house they bought for $140,000 in 1996 in National City, Calif., about 10 miles from the border. Letters from family and friends say they were devoted to their parents — a diabetic mother and a father with a heart condition.

The investigation began in May 2005 with an informant’s tip to U.S. Immigration and Customs Enforcement. Investigators installed cameras on poles where migrants were dropped off, planted undercover recording devices, put tracking instruments on Border Patrol vehicles and followed a smuggling load by airplane.

Nick, Raul’s attorney, hinted at his defense in a court filing that said the prosecution hinges on “unreliable witnesses who have a strong motive to lie.” He said surveillance yielded nothing to incriminate his client.

Fidel’s attorney, Zenia Gilg, wrote that the prosecution rests largely on two alleged accomplices who were promised leniency for testifying and “inconsistent statements” from migrants.

The brothers joined the Border Patrol when the agency was rapidly growing and moved up the ladder. Raul earned $82,859 as an agent in 2005, while Fidel made $77,803.

Raul’s bank account had “unexplained cash deposits” of $61,121 during 2005 and 2006, according to prosecutors who say he traveled to the Cayman Islands in March 2006. One alleged accomplice told authorities that Raul spoke of having bank accounts in the Cayman Islands and Argentina to escape detection.

The brothers suddenly resigned for emergency family health issues, saying exit interviews were impossible. A few days earlier, Fidel withdrew $10,000 from his North Island Credit Union account. One day before quitting, Raul reported that his 2000 Mercedes-Benz ML430 was stolen but, according to prosecutors, took it to Tijuana in an attempt to scam his insurance company.

Raul transferred ownership of the family’s National City home to his younger sister shortly after quitting. A year later, the brothers emptied their retirement accounts.

Raul’s attorney said the brothers “lived openly under their true names in Tijuana,” sending word to U.S. authorities that they were prepared to return to the United States. A July 2007 letter from their former attorneys to a prosecutor says they would surrender if charges were filed. A grand jury didn’t return an indictment until April 2008, four months before they were captured.

— Associated Press