By Ron Nixon, New York Times

WASHINGTON — In 2012, Joohoon David Lee, a federal Homeland Security agent in Los Angeles, was assigned to investigate the case of a Korean businessman accused of sex trafficking.

Instead of carrying out a thorough inquiry, Lee solicited and received about $13,000 in bribes and other gifts from the businessman and his relatives in return for making the “immigration issue go away,” court records show.

Lee, an agent with Homeland Security Investigations at Immigration and Customs Enforcement, filed a report saying: “Subject was suspected of human trafficking. No evidence found and victim statement contradicts. Case closed. No further action required.”

But after another agent alerted internal investigators about Lee’s interference in another case, his record was examined and he was charged with bribery. He pleaded guilty in July and was sentenced to 10 months in prison.

It was not an isolated case. A review by The New York Times of thousands of court records and internal agency documents showed that over the last 10 years almost 200 employees and contract workers of the Department of Homeland Security have taken nearly $15 million in bribes while being paid to protect the nation’s borders and enforce immigration laws.

These employees have looked the other way as tons of drugs and thousands of unauthorized immigrants were smuggled into the United States, the records show. They have illegally sold green cards and other immigration documents, have entered law enforcement databases and given sensitive information to drug cartels. In one case, the information was used to arrange the attempted murder of an informant.

The Times’ findings most likely undercount the amount of bribes because in many cases court records do not give a tally. The findings also do not include gifts, trips or money stolen by Homeland Security employees.

Throughout his campaign, President-elect Donald Trump said border security would be one of his highest priorities. As he prepares to take office, he will find that many of the problems seem to come from within.

“It does absolutely no good to talk about the building of walls or tougher enforcement if you can’t secure the integrity of the immigration system, when you have fraud and corruption with your own employees,” said an internal affairs official at the Department of Homeland Security who spoke on the condition of anonymity.

Although Homeland Security employees who have been caught taking bribes represent less than 1 percent of the more than 250,000 people who work at the department, investigators say the bribes and small numbers of people arrested and charged with bribery obscure the impact corruption can have on border security and immigration enforcement.

“Any amount is bad, and one person alone can do a lot of damage,” said John Roth, the inspector general at the Department of Homeland Security. “It doesn’t have to be widespread.”

Law enforcement experts say the bribing of border and immigration agents is not surprising. As security along the border has tightened with the addition of fences, drones and sensors, drug cartels and human smugglers have found it increasingly more difficult to operate.

“So it makes sense that cartels would target and try to corrupt border interdiction agents,” said Fred Burton, chief security officer at Stratfor, a global intelligence company, and a former deputy chief of counterterrorism at the State Department’s Diplomatic Security Service. “It’s very similar to the tactics and tradecraft used by foreign intelligence services during the Cold War.”

Homeland Security officials, acknowledging that internal corruption is a problem, have hired more internal affairs investigators, provided ethics training and started to administer polygraph tests to new applicants, along with countersurveillance training to employees so they can recognize when they are being targeted by criminal organizations.

Customs and Border Protection, which has had dozens of its officers arrested and charged with bribery, said it had made additional changes to combat corruption. Jeh Johnson, the secretary of Homeland Security, in 2014 gave authority to the agency’s internal affairs office to conduct criminal investigations for the first time. And Mark Morgan, a former FBI agent who had investigated corruption on the border, was put in charge of the Border Patrol.

“Polygraphs have made it so we don’t hire people with significant problems,” said R. Gil Kerlikowske, commissioner of the customs agency. “The bigger problem is what happens to people who are already on board. These changes address that.”

Records show that the bribing of Homeland Security employees persists. In 2016, 15 have been arrested on, convicted of or sentenced on charges of bribery.

In February, Johnny Acosta, a Customs and Border Protection officer in Douglas, Arizona, was sentenced to eight years in prison for bribery and drug smuggling. Acosta, who was arrested as he tried to flee to Mexico, took more than $70,000 in bribes and helped smuggle over a ton of marijuana into the United States.

Last month, Eduardo Bazan, a Border Patrol agent in McAllen, Texas, was arrested and accused of helping a drug trafficking organization smuggle cocaine. According to court records, Bazan admitted to receiving $8,000 for his help. José Cruz-López, a Transportation Security Administration screener at Luis Muñoz Marín International Airport in San Juan, Puerto Rico, was arrested around the same time and accused of taking $215,000 in bribes to help smuggle drugs.

Corruption investigators said the case of former Border Patrol agent Ivhan Herrera-Chiang illustrates the damage a single compromised agent can cause. In 2013, he was sentenced to 15 years for providing sensitive law enforcement information to drug cartels.

Herrera-Chiang, who was assigned to a special undercover unit targeting the cartels in Yuma, Arizona, provided maps of hidden underground sensors, lock combinations to gates along the U.S.-Mexico border and the locations of Border Patrol traffic checkpoints to an individual who provided them to the cartels. The cartels used the information to bypass Border Patrol agents and transport methamphetamine, cocaine and marijuana into the country, according to court records.

Herrera-Chiang also entered law enforcement databases on his work computer to run drug seizure checks and even provided information on confidential informants in Mexico. That information included one informant whom federal law enforcement officers were able to locate before he could be killed, court records said. Herrera-Chiang admitted to receiving about $4,500 in bribes for his efforts, but his co-conspirator put the amount between $60,000 and $70,000.

“Corrupt C.B.P. law enforcement personnel pose a national security threat,” a Department of Homeland Security report released in May concluded. The report also revealed numerous problems with efforts to root out corruption among Border Patrol and customs agents. The report said the “true levels of corruption within C.B.P. are not known.”

Convicted former border and immigration agents give different reasons for taking bribes, from financial troubles to drug use. But for many, it was simple greed.

Records show that Border Patrol officers and customs agents, who protect more than 7,000 miles of the border and deal most directly with drug cartels and smugglers, have taken the most in bribes, about $11 million.

But the issue of bribery extends well beyond front-line agents at the border. Department of Homeland Security employees who enforce immigration and customs laws and provide citizenship benefits and aviation security have also been arrested or indicted on and convicted of charges of taking bribes.

Last month, Daniel Espejo Amos, a former immigration service officer at the U.S. Citizenship and Immigration Services in Los Angeles, pleaded guilty to taking $53,000 in bribes from immigration lawyers on behalf of 60 immigrants who were not eligible to become naturalized citizens of the United States. Amos certified that the immigrants met the requirements for citizenship, even though one person’s English-language skills were so poor that copies of test answers were given to him so he could memorize them for a naturalization interview.

Transportation security officers and screeners with access to secure areas of airports that could be used to smuggle weapons and even carry bombs onto planes have taken hundreds of thousands of dollars in bribes as well, records show.

Roth, the inspector general, said rooting out corrupt employees is a top priority for his office, which gets 300 to 400 cases a year alleging corruption. The office takes about 100 of the cases and sends the rest to internal affairs offices at ICE, Customs and Border Protection, the TSA and Citizenship and Immigration Services.

The Border Corruption Task Force, which is directed by the FBI and includes agencies from the Department of Homeland Security as well as the Drug Enforcement Administration, has also pursued dozens of corruption and bribery cases that have ended in convictions.

But the Homeland Security report released in May said Customs and Border Protection, the parent agency of the Border Patrol, currently lacks proactive programs to weed out corruption. Instead, the report said, the agency based its investigations on reporting from other employees, other government agencies or the public, by which time the corruption could have festered for decades.

The agency also needed to more than double the number of internal affairs criminal investigators to 550 from about 200, the report said. It said the agency’s 2017 budget calls for an increase of only 30 investigators.

James Tomsheck, the former head of internal affairs at Customs and Border Protection, said many of the problems the agency is facing with corrupt agents had to do with inadequate prehiring screening programs.

Background checks and polygraph tests have failed to weed out actual cartel members who were hired by the Border Patrol in some instances, he said.

To Learn More:

Border Protection Agency Accused of Failing to Add More Internal Corruption Investigators (by Elliot Spagat, Associated Press)

260 Homeland Security Employees Convicted of Crimes in 2011 (by Noel Brinkerhoff and David Wallechinsky, AllGov)