SAN DIEGO (AP) – Border Patrol Agent Oscar Antonio Ortiz brought a certain inside knowledge to his job policing the U.S.-Mexican frontier: He had come to the United States illegally and was once arrested and accused of trying to drive two illegal immigrants across from Mexico.

But his superiors did not know any of that when he applied for a job with the Border Patrol, because he had a fake birth certificate that said he was from Chicago.

None of that would come out until last August, when, after three years of distinguished service, Ortiz was arrested again and admitted smuggling at least 100 illegal immigrants into the country, sometimes by driving them in his Border Patrol truck.

On Friday, Ortiz, 29, was sentenced to five years in prison in one of a spate of corruption cases involving Border Patrol agents at a time when the agency is on a hiring spree.

Prosecutors had asked for about three years, but U.S. District Judge John A. Houston decided a stiffer punishment was required for Ortiz, who pleaded guilty to charges that included conspiracy to bring in illegal aliens and making a false claim to U.S. citizenship.

“You violated the sacred trust of your comrades,” the judge said. “As a link in the chain, they depended on you.”

Ortiz expressed remorse: “I was blind at the time I made my mistake of smuggling.”

Critics say the corruption cases raise questions about the hiring process at the Border Patrol as it grows from 11,700 agents now to 18,000 by the end of 2008 in an effort to tighten the nation’s borders.

“The more pressure there is to hire people quickly, the more dysfunction there is,” said Clark Ervin, former inspector general of the Department of Homeland Security, which oversees the Border Patrol.

So far this year, 25 Customs and Border Protection workers have been arrested on corruption charges. Eight have been convicted. Agency spokesman Todd Fraser said he did not know whether that marked an increase but noted it is a small percentage of the force.

The Border Patrol had found promise in Ortiz. A performance review in 2003 noted his “radiant, confident, poised and courteous demeanor,” Spanish fluency, exceptional grooming, punctuality and writing skills.

He had joined the Navy in 1998 after growing up in San Diego and working a construction job in Utah. During four years in the military, mostly aboard an amphibious assault ship, he collected awards including for good conduct.

Fraser said the agency had believed Ortiz was a U.S. citizen – a job requirement – and was unaware of his smuggling arrest, which took place shortly before he applied to the Border Patrol in October 2001. (He was accused of taking $400 to try to smuggle two people across the border, but was never actually charged.)

“There were no red flags,” Fraser said.

Investigators found Ortiz was really born in Tijuana, Mexico. His attorney, Stephen White, said in court that Ortiz’s mother obtained the fake birth certificate when Ortiz was 3, and Ortiz said he grew up thinking he was a U.S. citizen.

After Ortiz’s arrest, Customs and Border Protection, which includes the Border Patrol and border inspectors, checked the citizenship of its nearly 42,000 employees, Fraser said. He said he did not immediately know whether any other noncitizens were found.

Customs and Border Protection has seen a number of instances of corruption recently.

– Two agents in El Centro pleaded guilty this month to taking nearly $200,000 in bribes to release immigrant smugglers and illegal immigrants.

– Two inspectors in San Diego were arrested in June on smuggling charges. Prosecutors say one took cash and a Lexus to let people through his inspection lane.

– Two brothers who were Border Patrol agents in San Diego – one a former agency spokesman – disappeared last month while under investigation on suspicion of smuggling immigrants and drugs.

Ortiz worked with another agent to smuggle people near Tecate, a remote area east of San Diego. Wiretaps indicate they were paid $300 per immigrant for looking the other way when they crossed the border. If the agents drove the immigrants, they got $1,800 to $2,000 per person.

The other agent, Eric Balderas, pleaded guilty to conspiracy and awaits sentencing.

Agents usually patrol alone, making it difficult to spot corruption, said T.J. Bonner, president of the union representing Border Patrol agents.

“You’re assigned to an area, you radio-check to say everything’s all right and you’re out there alone for eight hours without seeing anyone,” Bonner said.

Ortiz would “go off on his own,” Bonner said. “After the fact, people said that was kind of strange that he would disappear.”

AP-ES-07-28-06 1542EDT