Ginger Thompson / New York Times News Service

The forecast called for record snowstorms, and Luis Octavio Lopez Vega had no heat in his small hide-out.

Thieves had run off with the propane tanks on the camper that Lopez had parked in the shadow of a towering grain elevator, near an abandoned industrial park. Rust had worn through the floor of his pickup truck, which he rarely dared to drive because he has neither a license nor insurance. His colitis was flaring so badly he could barely sit up straight, a consequence of the breakfast burrito and diet soda that had become part of his daily diet.

He had not worked in months and was down to his last $250.

Going to a shelter might have opened him to questions about his identity that he did not want to answer, and reaching out to his family might have put them at odds with the law.

“I cannot go on like this, living day to day and going nowhere,” Lopez, 64, said one night last winter. “I feel like I’m running in place. After so many years, it’s exhausting.”

Lopez, a native of Mexico, said in Spanish that he has lived under the radar in the Western United States for more than a decade. But while he blends in to the immigrant community, his predicament goes far beyond his immigration status.

Lopez played a leading role in what is widely considered the biggest drug-trafficking case in Mexican history. The episode — which inspired the 2000 movie “Traffic” — pitted the Mexican military against the U.S. Drug Enforcement Administration. Throughout the 1990s, Lopez worked closely with them both. He served as a senior adviser to the powerful general who was appointed Mexico’s drug czar. And he was an informant for the DEA.

His two worlds collided spectacularly in 1997, when Mexico arrested the general, Jesus Gutierrez Rebollo, on charges of collaborating with drug traffickers. As Washington tried to make sense of the charges, both governments went looking for Lopez. Mexico considered him a suspect in the case; the DEA saw him as a potential gold mine of information.

The United States found him first. The DEA secretly helped Lopez and his family escape across the border in exchange for his cooperation with its investigation.

Dozens of hours of testimony from Lopez about links between the military and drug cartels proved to be explosive, setting off a dizzying chain reaction in which Mexico asked the U.S. for help capturing Lopez, Washington denied any knowledge of his whereabouts and the DEA abruptly severed its ties with him.

The reserved, unpretentious husband and father of three has been a fugitive ever since, on the run from his native country and abandoned by his adopted home. For more than a decade, he has carried information about the inner workings of the drug war that both governments carefully kept secret. Camouflaging himself among the waves of immigrants who came across the border around the same time, with his callused hands and thrift-store wardrobe, Lopez works an assortment of low-wage jobs available to people without green cards.

The United States continues to feign ignorance about his whereabouts when pressed by Mexican officials, who still ask for assistance to find him, a federal law enforcement official said.

The coverup was initially led by the DEA, whose agents did not believe the Mexican authorities had a legitimate case against their informant. Other law enforcement agencies later went along, out of fear that the DEA’s relationship with Lopez might disrupt cooperation between the two countries on more pressing matters. “We couldn’t tell Mexico that we were protecting the guy, because that would have affected their cooperation with us on all kinds of other programs,” said a former senior DEA official who was involved in the case but was not authorized to speak publicly about a confidential informant. “So we cut him loose, and hoped he’d find a way to make it on his own.”

These are the opaque dynamics that undermine the alliance between the United States and Mexico in the war on drugs, a fight that often feels more like shadow boxing. Though the governments are bound together by geography, neither believes the other can be fully trusted. Lopez’s ordeal — pieced together from classified DEA intelligence reports and interviews with him, his family, friends, and more than a dozen current and former federal law enforcement officials — demonstrates why the mutual distrust is justified.

The absence of any facts to either condemn Lopez or exonerate him of corruption has wrought havoc on the former informant, and his fugitive’s existence has been a ball and chain on his family, whom he sees during sporadic rendezvous. They all exhibit symptoms of emotional trauma, bouncing among flashes of rage, long periods of depression, episodes of binge drinking and persistent paranoia.

During several long interviews, Lopez repeatedly said he was not guilty of any wrongdoing. He said he has refused to turn himself in to the Mexican authorities because he believes he will be killed rather than given a fair hearing. But years of living an anonymous, circumscribed life have been nearly as suffocating as a jail cell.

He starts most mornings at McDonald’s, where breakfast costs less than $2 for seniors and free Wi-Fi allows him to peruse Mexican newspapers on his battered laptop for hours, his mind replaying the life choices that landed him there.

“I risked my life in Mexico because I believed things could change. I was wrong. Nothing has changed,” Lopez said. “I helped the United States because I believed that if all else failed, this government would support me. But I was wrong again. And now, I’ve lost everything.”

The military steps in

Ballads were written in Mexico about the day in 1995 when the authorities took down Hector Luis Palma Salazar, known as “El Guero,” the fearsome kingpin of the Sinaloa cartel. Palma met his fate on the outskirts of Guadalajara in suburban Zapopan, a nexus for everybody who was anybody in the drug war.

Lopez served nearly two decades in the municipal police department there, most of them as chief. Politically astute and streetwise, he caught the attention of the DEA, which developed him as a confidential source during the mid-1990s and valued him for the reliability of his information.

Drug violence was raging. When things got too heated, Lopez sought backup from Gutierrez, a powerful ally whose territory spanned five Mexican states. It was part of a secret arrangement, Lopez said, in which his officers shared information about the cartels with the military and the general provided extra muscle to the Zapopan police.

At home, Lopez’s wife and three children lived surrounded by bodyguards and snipers. With her husband often absent, Soledad Lopez had her hands full with the children. Their oldest child, David, got his high school girlfriend pregnant. Luis Octavio failed eighth grade three times. Cecilia, the youngest, did not understand the tumult around her, and Soledad Lopez worked to protect her from it.

By the time Palma crossed his path, Lopez had retired to start a private security firm. Palma had been on his way to a wedding when his private plane crashed in the mountains near Zapopan. Federal police officers who were on the Sinaloa payroll swept him from the scene and hid him in a house belonging to a supervisor.

When Lopez’s security guards began receiving reports of suspicious activity there, they alerted him and the military. No one realized they had stumbled across one of the world’s most notorious drug traffickers until Lopez discovered a .45 Colt with the shape of a palm tree, or “palma,” encrusted on its handle in diamonds, rubies and sapphires.

“It could only belong to one person,” Lopez said.

The arrest was hailed on both sides of the border to justify the unprecedented role the Mexican military was beginning to play under President Ernesto Zedillo. The DEA had long been pressuring Mexico to deploy the military against the cartels instead of the federal police, which often worked with traffickers instead of against them.

The agency was already secretly collaborating with Gutierrez. Ralph Villarruel, a veteran DEA agent who had been working with Lopez, said he pursued suspects the general believed were in hiding in the United States and seized loads of cocaine moving across the border. In return, he said, the general allowed him “unbelievable access” to crime scenes, suspects and evidence.

By December 1996, Zedillo elevated Gutierrez to run counternarcotics efforts as the director of Mexico’s National Institute to Combat Drugs. The move was a victory for the administration of President Bill Clinton, which had put in effect the North American Free Trade Agreement and orchestrated a $50 billion bailout of the Mexican economy. Cracking down on drug traffickers hardly seemed too much to ask of the United States’ neighbor.

In Gutierrez, who had the face and demeanor of a pit bull, the United States saw the no-nonsense partner it had been seeking. The administration invited him to Washington for briefings, and the United States’ drug policy coordinator, Gen. Barry McCaffrey, praised him as a soldier “of absolute, unquestioned integrity.”

It seemed a head-spinning turn of events for a little-known military leader who could count his suits on one hand and had never traveled outside Mexico. When the general asked Lopez to be his chief of staff, though, he was apprehensive about moving to the capital. But the general insisted.

“Going to work in Mexico City felt like falling into a snake pit,” Lopez said. “I had a bad feeling about the whole thing.”

‘There’s a problem’

Less than three months later, Lopez was in Guadalajara for the birth of a grandchild when he suspected something had happened to his boss. He had been calling Gutierrez for days without success. Finally, he got the general’s driver on the phone.

“I don’t know where he is,” the driver said, according to Lopez. “You shouldn’t call here anymore. I can’t talk on this phone. Perhaps they’re already listening. What the hell, you need to know. There’s a problem.”

When Lopez hung up and called the military base in Guadalajara, the commander there summoned him to a “counternarcotics operation.”

“I didn’t know exactly what was going on,” Lopez said, “but I knew that a trap was waiting for me at the base.”

He told his family to leave Zapopan and warned his aides to stay away from the base. For several days, Lopez kept out of sight, camping out in abandoned barns and beneath bridges while the military seized his house and searched his belongings.

On Feb. 19, 1997, the Mexican defense minister, Enrique Cervantes Aguirre, held a dramatic televised news conference and accused Gutierrez of using his authority to help protect Amado Carrillo Fuentes, a drug baron nicknamed “The Lord of the Skies,” for his use of converted jetliners to move multiton shipments of cocaine.

The defense minister said that when Gutierrez was confronted with evidence of the association, he collapsed from what appeared to be a heart attack.

With checkpoints going up around Guadalajara, it seemed impossible for Lopez to leave, and he was so well known he feared he could not hide for long. Borrowing a page from the drug trafficker’s playbook, Lopez went to see a plastic surgeon to alter his appearance. Using a false name, he handed the surgeon $2,000 in cash and got a face-lift.

In Washington, Congress called on the White House to void Mexico’s standing as a reliable ally in the drug war, a move that could lead to sanctions against a country buying up American exports. The episode threatened security cooperation between the two countries. The Justice Department ordered the DEA to explain how it could have missed evidence that Gutierrez was dirty. The DEA turned to Villarruel, who began looking for Lopez.

Most of Lopez’s staff members had disappeared, said Villarruel, who learned that the military had rounded them up for questioning. “My sources were dropping like flies,” said Villarruel, a veteran agent and native of East Chicago, Ind., who has family roots in Guadalajara. “One day I’d be talking to a guy, the next day he’d be dead.”

The DEA’s message reached Lopez in May 1997, just as he and his family thought they had run out of options.

Later that May, the DEA opened an escape hatch, offering the family a haven in the U.S. and arranging work permits and visas. Making the trip were Lopez’s wife, three children, daughter-in-law and two grandchildren. The family members made their way to Utah, where they had a friend.

Lopez followed a couple of weeks later. Wearing a navy blue suit and a fedora he bought for the journey, he arrived in the United States with a briefcase packed with his life’s savings, $100,000, and visions of starting over.

On the run

In January, Lopez and his son Luis Octavio headed to Wendy’s for a 99-cent hamburger special. When his son handed over $2 for their order, a few cents short of the total, an embarrassed Lopez had to tell him that he could not cover the difference.

Money, or the lack of it, has been the hardest part of living in hiding, Lopez said. His savings ran out long ago, and most employers are not interested in a 64-year-old man with no Social Security card or documented work history. He has tried day jobs as a dishwasher and a construction worker, but his back is not strong enough.

His dire circumstances reflect a precipitous fall from his arrival in the United States as a prized informant. The inside account he gave to Villarruel and other DEA officials amounted to a bombshell, according to former agents involved with the case and classified intelligence reports obtained by The New York Times.

He claimed that the Mexican military was negotiating a deal to protect the cartels in exchange for a cut of their profits. Lopez specifically accused several top officers of being involved, saying some had asked the cartels for $2,000 per kilogram of cocaine that passed through Mexican territory.

As a down payment, cartel operatives delivered satchels packed with tens of millions of dollars to senior members of the military, according to Lopez. He also accused American-trained counternarcotics units of allowing kingpins to escape during sting operations.

“It is highly likely that military officials probably wanted to continue to profit from an ongoing relationship with the drug traffickers,” concluded one intelligence report.

Lopez said he told the DEA that he did not believe Gutierrez was among those conspiring with traffickers. But the intelligence reports suggested that the general had ties to the Juarez cartel, and that the relationship may have posed a threat to other military officers who were being paid by rival drug-trafficking organizations.

By 1998, some of that information began appearing in congressional briefings and newspaper reports, pitting the DEA against the White House, which opposed any measures that would undermine the United States’ second-largest trading partner. The DEA accused Mexico of failing to live up to its security commitments, and it advocated taking action that could lead to economic sanctions. “There was definitely a split between us and the White House over Mexico,” a former senior DEA official said.

Mexico, which was still trying to track down Lopez, intensified its search in 1999. The Foreign Ministry requested Washington’s assistance to determine whether he lived in the United States, a senior American federal law enforcement official said. United States marshals reported back that he did.

Later that year, Villarruel asked Lopez to meet him at a Denny’s in San Diego. Villarruel arrived alone and had a hard time looking him in the eye. “I told him I had orders from Washington that I couldn’t have anything to do with him no more,” Villarruel recalled. “I could tell there was some kind of pressure, but I couldn’t tell if it was from Congress, or from Mexico, or where. All I knew was that ... I could get in trouble.”

Defying orders, agent Ralph Villarruel warned Luis Octavio Lopez Vega to watch his back.