Kilmar Armando Abrego Garcia, all of 16, called his older brother in distant Maryland with startling news. He had made it to the Texas border. He had escaped.

In his family’s telling, this is how his American journey began. They say that for years in El Salvador, a gang called Barrio 18 had terrorized them, extorting money from the mother’s small tortilla and pupusa business, threatening to leave them all dead in a ditch — and targeting young Kilmar, in and out of school, with increasing menace.

“‘They will appear in black bags,’” his mother said through tears, recalling phone messages from the gang. “Those were the words they would say.”

Seeing a dim future, the teenager had slipped away to follow the worn, treacherous path known to so many other migrants before him, including his older brother. North, across desert and river, into Mexico, and then into the United States.

Over the next dozen years, Mr. Abrego Garcia would call Maryland his home. He would work in construction. Marry. Help to raise three children, all with special needs. He would also be repeatedly accused by his wife of verbal and physical abuse — and be labeled as a gang member by the president of the United States.

On March 15, the tumultuous American journey of Mr. Abrego Garcia returned him to South Texas, in restraints. There, on the tarmac of Harlingen Airport, loomed three large airplanes bound for El Salvador.

Two were reserved for undocumented immigrants being deported without the constitutional right to due process, on the allegation that they belonged to a well-known Venezuelan gang. The third plane was for dozens of other immigrants who, according to the government, had at least been given the chance to argue their case in a hearing.

Whatever their past, all the detainees — more than 260 — were being sent by the Trump administration to a Salvadoran maximum-security prison notorious for its inhumane conditions.

While captors and captives waited for takeoff, some names fell from the third plane’s manifest for various reasons, and Mr. Abrego Garcia’s name was added. This was a mistake — a perverse upgrade.

Six years earlier, a federal immigration judge had expressly prohibited the government from returning Mr. Abrego Garcia to his native El Salvador, where gang activity might still pose a threat to his life. Yet here he was, in a Kafkaesque twist, being sent back in chains to that very country.

The reason: the Trump administration’s assertion that he was part of a Salvadoran-American criminal gang called MS-13 — an assertion based partly on his clothes and tattoos.

The New York Times conducted nearly two dozen interviews in Maryland and El Salvador, and reviewed court documents and recordings in several jurisdictions, to construct a fuller portrait of Mr. Abrego Garcia. A sheet metal worker with no criminal record but brushes with law enforcement, he has become an avatar for both sides of a roiling American debate: those who support the lengths taken by President Trump to crack down on illegal immigration; and those who believe his efforts amount to cruel and Constitution-defying overreach.

Whether Mr. Abrego is an MS-13 gang member — as, with equal vehemence, the Trump administration insists and his family denies — remains unclear.

“Perhaps, but perhaps not,” wrote Judge J. Harvie Wilkinson III, a conservative jurist on a federal appeals court in Virginia, pondering whether Mr. Abrego Garcia was a gang member.

“Regardless, he is still entitled to due process.”

On the tarmac in Harlingen, an Airbus A320 began to hum and whine. Just three days earlier, Mr. Abrego Garcia was driving in suburban Maryland, his 5-year-old disabled son secure in a car seat in the back, when an officer pulled him over for what seemed like a routine traffic stop.

Now he was the one restrained in a seat, on an airplane separating from American soil as the sun began to set in the clear Texas sky.

The working-class neighborhood of Los Nogales, on the hilly edge of San Salvador, is modest but inviting, the vibrant colors of its cinder-block homes heightened by bougainvillea and lush gardens of potted plants. It was here that Mr. Abrego Garcia lost the puckishness of boyhood to the constant threat of gang violence.

He was born in 1995 to Armando Abrego, a former soldier and police officer who drove a taxi, and Cecilia Garcia de Abrego, who sold homemade tortillas and pupusas — thick, stuffed flatbreads — from the garage of their narrow, two-bedroom home. Neighbors remember Kilmar, the youngest of the couple’s four children, as a soccer-loving scamp who enjoyed stirring things up: ringing doorbells and running away, talking fresh to elders, getting into scraps.

“Honestly, yes, he was very mischievous,” recalled a close childhood friend named Carlos, who asked that his full name not be used for fears about his safety. “But it was never like — I mean, whether he did things with good or bad intentions, I couldn’t really say. But I do know he liked to play pranks and that he liked to stir up trouble.”

The friend’s mother, who also asked that her name be withheld for safety reasons, said that Mr. Abrego Garcia’s antics sometimes went too far, prompting the parents of other children to march up to his mother’s tortillería to demand that the child be reined in.

“He was a restless child,” said Blanca Galdamez, a next-door neighbor. “I consider him to have been a normal child.”

Mr. Abrego Garcia’s mother agreed. During a recent interview, she smiled when recalling how he and his siblings helped the family business by buying supplies and making deliveries. “We sold pupusas four days out of the week and tortillas seven days a week,” Ms. de Abrego recalled. “He collaborated in that.”

But the rise of criminal gangs had begun to color everyday Salvadoran life, with the grisly aftermath of their violence vividly portrayed on the nightly news. Residents of Los Nogales say they were mostly spared, with no graffiti to mark their neighborhood as the territory of MS-13 or Barrio 18. But schools around the city, including Kilmar’s, were becoming hotbeds of gang violence.

Cesar Abrego Garcia, Kilmar’s older brother, said he could feel the violence closing in. He headed north into Mexico and, eventually, the United States.

“It was tough to leave my siblings, my family, to be here alone,” said Cesar, who is now an American citizen and a licensed electrician in Maryland. “But I believe it was worth it because I could say that maybe I would even be dead if I had stayed.”

In his phone calls back home, Cesar said, he would hear that Barrio 18 was extorting money from the family’s pupusa business and targeting his younger brother.

“They had to disconnect the phone,” he said.

One day in 2011 or 2012, Kilmar began his daunting journey to the United States, probably with the help of paid smugglers. Before long he made his way to Prince George’s County in Maryland, joining the ranks of undocumented laborers who, out of necessity, become jacks-of-all-trades, working in construction, remodeling homes and repairing air-conditioning systems.

They find these jobs through relatives, or word of mouth, or by mustering at designated gathering spots — the parking lot, say, of a Home Depot.

By 2016, life had given Jennifer Vasquez a lot to handle. Born and raised in Fairfax, Va., she was 20 years old, working at a chiropractor’s office, emerging from an abusive relationship and raising two young children who required a lot of attention and care. Her 2-year-old daughter had epilepsy, and her 1-year-old son had autism.

Then a friend at work introduced her to a young laborer named Kilmar Abrego Garcia. It took a couple of years, but finally, in 2018, they had their first date during their work breaks. They ate lunch in his car, at the construction site where he was toiling. He opened a bag and pulled out two juice boxes for them — and two lollipops for her children.

“An instant spark,” she said.

After a few months, they were living together. Recalling how Mr. Abrego Garcia ran errands, did school pickups and attended to her seizure-prone daughter, Ms. Vasquez said, “I’ve always said that blood doesn’t define family.”

But this new, cobbled-together family faced challenges. In August 2018, Ms. Vasquez’s former partner, a construction worker named Edwin Trejo Ramos, filed a court motion seeking immediate custody of their two children, claiming in part that they were in danger because she was “dating a gang member.”

A judge deemed the matter not an emergency, and the case was later dismissed, in early 2019. In November of that year, Mr. Ramos was charged with raping a 13-year-old girl. He was eventually convicted and sentenced to prison.

Ms. Vasquez learned that she and Mr. Abrego Garcia would be having a child, and her pregnancy carried high medical risk. With constant appointments and weekly injections, she said, her partner urged her to rest as much as possible while “he would do whatever he could to pay our bills.”

That is what Mr. Abrego Garcia was trying to do on March 28, 2019. After driving his pregnant girlfriend to her job, he stood with three other men in a spot designated for day laborers outside a Home Depot in the Washington suburb of Hyattsville, Md., where the sides of trucks in the parking lot say, “Rent Me Starting at $19.” He was hoping to be hired for the day, motivated in part by the image on his phone: a sonogram image of his yet-to-be-born child, who he had just learned was a boy.

A man approached the laborers as they chatted, but he was not a contractor looking to hire; instead, he was a Hyattsville police officer who thought they were loitering. Two of the men, neither of them Mr. Abrego Garcia, tossed plastic bottles containing marijuana under a parked vehicle.

All four men were handcuffed and taken to the Hyattsville station of the Prince George’s County Police Department for interviews. An officer with experience investigating gangs identified one man as “Bimbo,” a member of the MS-13 Sailors clique with an extensive criminal history, and a second man as another gang member called “Maniaco.” As for the third man, the officers “were unable to determine his gang affiliation” and “he was sent on his way,” according to a police report labeled “Gang Field Interview Sheet.”

That left Mr. Abrego Garcia, who was described as 5-foot-7, about 200 pounds, with short hair and a beard. He wore a Chicago Bulls hat and a hooded sweatshirt with a depiction of “rolls of money covering the eyes, ears and mouth of the presidents on the separate denominations.”

The report asserted that the outfit was “indicative of the Hispanic gang culture,” and that the Bulls hat represented “a member in good standing with the MS-13.” In addition, it said, a reliable, unnamed source had identified Mr. Abrego Garcia as a member of MS-13’s Westerns clique who was known as “Chele.”

Mr. Abrego Garcia admitted to being in the United States without proper documentation, but fiercely denied gang membership; indeed, he had no record beyond several traffic infractions. What’s more, MS-13’s Westerns clique operates from the Long Island town of Brentwood, but his lawyers would later say he had never lived in New York State. As for the sweatshirt, which depicted rolls of money and the face of Benjamin Franklin — not presidents, as the police report said — Ms. Vasquez would later say she bought it for her boyfriend after seeing the design on Fashion Nova, a clothing website.

The report and one of its authors would have other problems. For one, the report indicated that Mr. Abrego Garcia was being detained in connection with a murder investigation — a reference made nowhere else and never again. For another, a gang unit officer involved in the encounter, Ivan Mendez, would be suspended days later and eventually fired; he would later plead guilty to misconduct after admitting to providing confidential information to a woman whom he paid for sex.

Ms. Vasquez spent that night panicking, not knowing why Mr. Abrego Garcia hadn’t collected her from work, not knowing where he was or why his phone was turned off. But the next morning, he called with an explanation: He was now in the custody of Immigration and Customs Enforcement.

The couple found themselves in the hell of uncertainty. She was dealing with her risky pregnancy, caring for two children with special needs, trying to keep things together on one income, working as an advocate for her husband and fearing that their child would not know his father. And he was behind the curling razor wire of a detention center about 20 miles from home, struggling to prove that he was not a gang member.

In late June, three months after Mr. Abrego Garcia’s arrest, a wedding ceremony was held at a venue not featured in bridal brochures: the Howard County Detention Center in Jessup, Md. There, separated by a glass partition, Ms. Vasquez and Mr. Abrego Garcia exchanged vows in the presence of a pastor. Unable to touch each other, they exchanged rings with the help of a corrections officer.

In August, Ms. Vasquez underwent a C-section. Their boy was born with a congenital ear deformity and, it would later be determined, was autistic and unable to speak.

The birth came between immigration court proceedings in which Mr. Abrego Garcia sought to fight his deportation by requesting a humanitarian exception that would allow him to remain in the United States, citing the gang harassment of his family in El Salvador. The government argued he should be denied that bid because of his suspected gang membership.

Lucia Curiel, Mr. Abrego Garcia’s lawyer at the time, recalled that the government presented a particularly aggressive case against her client. His hearing lasted two days over several months, when similar proceedings usually take only a few hours. Nevertheless, he prevailed, with the immigration judge granting him a special status, “withholding from removal,” that indefinitely prohibited the government from deporting him to El Salvador.

“The judge would not have found him credible or granted any relief if he had believed Kilmar was a gang member,” Ms. Curiel said.

For now, at least, Mr. Abrego Garcia was free to go.

In a storybook world, Mr. Abrego Garcia would simply return to Prince George’s County, never again to draw the attention of law enforcement. He would blend into the multiracial fabric of the county, where more than half the residents are African American and a quarter are Hispanic or Latino. In some neighborhoods, street vendors set up stands to sell rolled tortilla chips, papas fritas or flavored ices.

But life for Mr. Abrego Garcia continued to be fraught.

Released from detention after seven months, he held his infant son for the first time, became emotional when he reunited with the two older children and, gradually, returned to the daily challenges of work and family. But his wife said his incarceration had changed him.

“Once he came out, maybe like a month after he was out, he changed a lot with me and my kids, and my other two kids,” Ms. Vasquez told a Maryland judge in 2020. “Like, he would yell at them and me for anything. Any little thing, it would bother him.”

He also became short-tempered and violent, according to court documents from two protective orders sought by his wife, as well as audio recordings of her court appearances obtained by The Times. One month after Mr. Abrego Garcia’s release, according to those documents and recordings, he began to physically abuse Ms. Vasquez, prompting her to fill out paperwork to secure a protective order against him that December. But, as she told a judge in 2020, she never showed up for court in that case, testifying that Mr. Abrego Garcia’s family had persuaded her not to follow through with it.

But the abuse continued into 2020, she said in testimony and in court records. Mr. Abrego Garcia was kicking her, shoving her, grabbing her hair, slapping her and making everyone in the house afraid, she said.

“Also, he breaks, like, everything in the house,” Ms. Vasquez told a district court judge in August 2020, according to the audio recordings, when the judge asked for more evidence of the abuse. “That’s the first thing that my son told the officer: ‘Can you please tell him not to break anything?’”

Ms. Vasquez noted that her husband “does use drugs,” but that he had no access to firearms.

The judge granted a temporary protective order, ruling that Mr. Abrego Garcia have no contact with Ms. Vasquez and the children, not abuse or harass them, and move out of their home until the hearing for the final protective order. The judge also gave Ms. Vasquez custody of the couple’s 11-month-old son.

Eight days later, Ms. Vasquez filed to rescind the order, saying that Mr. Abrego Garcia’s family wanted him to be part of their son’s first birthday celebration and that he had agreed to continue counseling. She did not appear for a subsequent hearing, held in late September, and her petition for a protective order was dismissed.

Less than a year later, Ms. Vasquez filled out another request for a protective order against her husband. In that document, she described an incident in May 2021 in which Mr. Abrego Garcia punched her and scratched her left eye and, later that day, tore her clothes off and grabbed her arm so hard he left marks. But a month later she again failed to appear for a hearing, and the matter was dropped.

When asked last week about her reports of domestic violence several years ago, Ms. Vasquez said that she and her husband had gone through “a rough patch” driven by the trauma of his protracted detention, but had overcome that difficult time through counseling.

“We closed that chapter,” Ms. Vasquez said. “We were mature enough to look for help.”

Mr. Abrego Garcia’s American life went on. The trepidation known to undocumented immigrants remained ever-present, the occasional encounters with law enforcement not at an end.

According to records released last month by the Department of Homeland Security, Mr. Abrego Garcia notified immigration officials in late October 2022 that he wanted to move to Houston to be closer to his parents. Just five weeks later, he was driving back to Maryland — with eight passengers — when a highway patrol officer in Tennessee pulled him over for speeding.

In Homeland Security’s version of the trooper’s account, Mr. Abrego Garcia explained that he had left Houston three days earlier and was transporting people in his boss’s car to work in construction in Maryland. But there was no luggage, and the passengers all gave Mr. Abrego Garcia’s home address as their own — leading one officer to suspect the possibility of human trafficking.

In the end, Mr. Abrego Garcia was let off with a warning citation for driving with an expired license.

Back in Maryland, the couple rose most weekdays at 4:30 in the morning. A union member, he would join his sheet metal crew by 5:30 a.m., all the while hoping that the five-year apprenticeship program he was in would to advancement and better pay. She would drop the children at school before working the front desk at a dentistry office. He would pick the children up in the afternoon and help with homework and activities while she prepared dinner. There were soccer games, dance practices, weekend takeout dinners and the occasional outing on Cesar Abrego Garcia’s boat.

Particular care was given to the youngest, nonverbal, child. Because loud noise would unsettle the boy, Mr. Abrego Garcia did his best to secure doors and soundproof rooms, his wife said, and he watched YouTube tutorials for tips on how to keep his family safe.

The afternoon of Wednesday, March 12, carried the promise of spring, with few clouds and a temperature in the mid-60s. Mr. Abrego Garcia was headed home, his work shift ended, his 5-year-old son in the back seat of his vehicle, secured in a car seat designed for children with disabilities.

But while he drove along Baltimore Avenue in the Maryland suburb of College Park, Mr. Abrego Garcia was told to pull over by a law enforcement officer. He turned into the parking lot of an Ikea and stopped outside a Buffalo Wild Wings restaurant.

As this was happening, Mr. Abrego Garcia called his wife, who told him to put her on speaker phone. She heard someone tell him to turn the engine off and step out of the car. She heard her husband say that he had a son with special needs in the back seat. She heard the officer hang up her husband’s phone.

Minutes later, someone saying they were with the Department of Homeland Security called Ms. Vasquez to inform her that she had 10 minutes to collect her son, or child protective services would be contacted.

She arrived a few minutes later to find her crying 5-year-old still strapped in his car seat and her husband sitting on a curb, his hands cuffed behind him. He was in a fluorescent yellow safety shirt that workers wear on construction sites.

The only explanation the distraught Ms. Vasquez received was that her husband’s “immigration status had changed.”

In the moment, it was unclear why a sheet metal worker with a child in the back seat of his car had been pulled over and handcuffed. But it came at a time when federal immigration agents were scrambling under pressure from the White House to meet one of President Trump’s more audacious political promises: to deport as many as one million immigrants from the United States in his first year in office.

Mr. Abrego Garcia called his wife that night from a detention center in Baltimore, and the questions he said he had been asked suggested that immigration agents had had him in their sights. They asked about his family’s visits to Don Ramon, a restaurant in Silver Spring that specializes in Mexican and Salvadoran food. They asked about a photo they had of him playing basketball with others at a local court. Who were those people?

And they accused him of being in MS-13 — a false, inflammatory allegation, his wife said, that she and her husband had thought was well behind them.

In the days ahead, as outrage grew over the deportation of hundreds to a Salvadoran prison system notorious for human rights violations, Mr. Abrego Garcia would be widely referred to in headlines around the world as the “mistakenly deported Maryland man.” Although much about him remains unknown, he came to personify the Trump administration’s determination to rid the United States of illegal immigrants — in part by defying the protection enshrined in the U.S. Constitution, that no person shall be deprived of life, liberty or property without the due process of law.

“The judicial process is for Americans,” Stephen Miller, Mr. Trump’s homeland security adviser, would say in a social media post. “Immediate deportation is for illegal aliens.”

The federal government would admit its mistake in deporting Mr. Abrego Garcia, whose whereabouts in the Salvadoran prison system have become unclear, yet resist doing much to correct that mistake. Instead, the government would double down on its assertion that he was a gang member.

Mr. Trump would display a digitally altered photo of Mr. Abrego Garcia’s tattooed hands as proof. Vice President JD Vance would erroneously call him a convicted gang member. A top homeland security official would falsely say in a social media post that he had been “found with rolls of cash and drugs.” Homeland Security would release what it would call a “bombshell” report on the “Kilmar Abrego Garcia suspected human trafficking incident” — in reference to the Tennessee traffic stop.

Ms. Vasquez, meanwhile, would share the devastating effect on their family — how their youngest child sought comfort in the scent of his absent father’s work shirts — as their lawyers fought for Mr. Abrego Garcia’s return in various courts. Ultimately, the Supreme Court would rule that the White House must take steps to “facilitate” his release from Salvadoran custody.

The White House would stonewall, prompting Paula Xinis, a federal judge in Maryland, to begin an inquiry into whether the administration had willfully violated her orders. But she would pause the proceedings at the government’s request after a cryptic Justice Department filing that referred to “diplomatic discussions” between the State Department and El Salvador.

Throughout, no one in the Trump administration would seem willing or able to answer the basic question posed by Judge Wilkinson: “The government has conceded that Abrego Garcia was wrongly or ‘mistakenly’ deported. Why then should it not make what was wrong, right?”

All this would transform Mr. Abrego Garcia into a complicated symbol, an international figure representing the unease and uncertainty in the United States in 2025.

For now, though, he was just a man sitting on a curb, the afternoon sun on his face. Handcuffed and crying, he was a mile from his American home, and three days from being sent in shackles to the home country he thought he had left for good.