A portion of the U.S.-Mexico border wall in Douglas.

Depositing $500,000 into Mexican bank accounts and repeatedly lying on background checks led to a three-month prison sentence for a former Douglas-based Border Patrol agent.

Oscar Cornejo, 39, pleaded guilty in September to making false statements about previous criminal charges filed against him and about his border-crossing history, U.S. District Court records show.

Cornejo, who was fired after 15 years as an agent and rising to be a supervisor with a six-figure income, also admitted to concealing assets from a bankruptcy court. But he said the $500,000 came from cyclically depositing his paychecks into ATMs in Arizona and withdrawing the money in Mexico to take advantage of the currency exchange rate.

The deposits were made from May 2016 to March 2017, prosecutors said. In one of the examples included in court records, Cornejo used three U.S. banks to deposit into two Mexican bank accounts $4,060 on Feb. 3, 2017; $4,316 the next day; and $4,980 the following day.

Some of Cornejo’s bank accounts were closed because of suspicious activity, and Cornejo told bank officials the activity was due to his wife running a business in Mexico, federal prosecutor Susanna Martinez told Judge Cindy K. Jorgenson at a sentencing hearing Wednesday.

“It’s absurd for him to say, ‘I made all this money on the exchange rate,’” Martinez said. “Do you know how many people would do that if they could make $500,000?”

Investigators traced his Border Patrol salary and could see it was “separate” from the $500,000, Martinez said.

“You can’t take anything Mr. Cornejo says as truthful or forthcoming,” Martinez said.

Jorgenson said Cornejo displayed an “attitude of dishonesty,” but sentenced him well below the 24 months requested by federal prosecutors, in part because of Cornejo’s recent cancer diagnosis.

“I’m really sorry about this situation,” Cornejo told Jorgenson. “My intentions were never to do any harm.”

During his January background check, Cornejo said he traveled to Mexico twice in the previous seven years. He wrote in the form that “I do sometimes go have dinner across the border in the local restaurants.”

His border-crossing history showed 1,200 crossings from 2012 to 2017, court records show. Investigators also found he was building a house in Agua Prieta, the Mexican city directly across the international border from Douglas.

Border Patrol agents are not allowed to have a foreign residence, Martinez said.

Cornejo said he lived in Douglas, but surveillance and border crossing records showed he entered the United States prior to his shifts, returned to Mexico after his shifts, and spent most of his days off in Mexico, according to the June 9 criminal complaint.

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Cornejo is a native of Peru who came to the United States when he was 5 years old, federal public defender Eric Rau wrote in a sentencing memorandum. Cornejo’s wife is a native of Agua Prieta and a lawful permanent resident of the United States.

They owned a home and lived in Douglas, but they started living intermittently in Agua Prieta in 2012. They rented a home there and started building a house in 2015 in hopes of saving money on rent, Rau said.

In each background check, Cornejo also said he had never been charged with a felony. Prosecutors said he was charged in Florida in 1996 with two counts of retaliating against a witness and one count of aggravated battery.

Cornejo was 17 years old at the time of the charges, which came after he and two friends assaulted witnesses who implicated his younger brother in a burglary, Rau wrote. He was sentenced to two years’ probation.

He was hired by the Border Patrol in 2002 during a “massive Border Patrol hiring surge in the aftermath of 9-11,” Rau wrote. The agency apparently never ran a background check, he wrote, “an oversight that appears widespread by the Border Patrol during that hiring surge.”

Despite his income as a Border Patrol supervisor, Cornejo and his wife struggled financially, Rau wrote. They filed for bankruptcy and were required to make 60 monthly payments of about $2,400.

Prosecutors wrote in a sentencing memorandum that Cornejo previously was suspended for lying during a traffic stop and he was the key witness in a human-smuggling prosecution that led to an acquittal.

Contact reporter Curt Prendergast at 573-4224 or cprendergast@tucson.com or on Twitter @CurtTucsonStar