On the Friday afternoon after Thanksgiving, Randal Quran Reid was driving his white Jeep to his mother’s home outside Atlanta when he was pulled over on a busy highway. A police officer approached his vehicle and asked for his driver’s license. Mr. Reid had left it at home, but he volunteered his name. After asking Mr. Reid if he had any weapons, the officer told him to step out of the Jeep and handcuffed him with the help of two other officers who had arrived.

“What did I do?” Mr. Reid asked. The officer said he had two theft warrants out of Baton Rouge and Jefferson Parish, a district on the outskirts of New Orleans. Mr. Reid was confused; he said he had never been to Louisiana.

Mr. Reid, a transportation analyst, was booked at the DeKalb County jail, to await extradition from Georgia to Louisiana. It took days to find out exactly what he was accused of: using stolen credit cards to buy designer purses.

“I’m locked up for something I have no clue about,” Mr. Reid, 29, said.

His parents made phone calls, hired lawyers and spent thousands of dollars to figure out why the police thought he was responsible for the crime, eventually discovering it was because Mr. Reid bore a resemblance to a suspect who had been recorded by a surveillance camera. The case eventually fell apart and the warrants were recalled, but only after Mr. Reid spent six days in jail and missed a week of work.

Mr. Reid’s wrongful arrest appears to be the result of a cascade of technologies — beginning with a bad facial recognition match — that are intended to make policing more effective and efficient but can also make it far too easy to apprehend the wrong person for a crime. None of the technologies are mentioned in official documents, and Mr. Reid was not told exactly why he had been arrested, a typical but troubling practice, according to legal experts and public defenders.

“In a democratic society, we should know what tools are being used to police us,” said Jennifer Granick, a lawyer at the American Civil Liberties Union.

A Contract With Clearview AI

In a panic, Mr. Reid’s family immediately retained an Atlanta lawyer from the Cochran Firm. He could not get Mr. Reid out of jail, and he struggled to gather more information. He suggested that the family members hire someone in Louisiana, so they cold-called law firms in Jefferson Parish and Baton Rouge until they found Thomas Calogero, a criminal defense lawyer. They retained him that Sunday.

Mr. Calogero found out that Mr. Reid was accused of the summer thefts of two Chanel purses and a brown Louis Vuitton bag, collectively worth almost $13,000, from Second Act, a consignment store on the outskirts of New Orleans. Mr. Calogero went to the store and talked to the owner, who showed him a still from a surveillance camera. He realized that one of the alleged fraudsters looked like Mr. Reid, but the man was heavier.

“The guy had big arms, and my client doesn’t,” Mr. Calogero said. A Jefferson Parish sheriff’s officer insisted it was a “positive match,” language that made Mr. Calogero believe that facial recognition technology had been used, and he spoke to the New Orleans news outlet NOLA.com about what he believed had happened.

A person with direct knowledge of the investigation confirmed to The New York Times that facial recognition technology had been used to identify Mr. Reid. Yet none of the documents used to arrest him disclosed that.

Andrew Bartholomew, the Jefferson Parish financial crimes detective who sought the warrant to arrest Mr. Reid, wrote in an affidavit only that he had been “advised by a credible source” that the “heavyset black male” was Mr. Reid. Reached by phone, Detective Bartholomew declined to comment.

“It’s untenable to me as a matter of basic criminal procedure that people who are subject to arrest are not informed of what got them there,” said Barry Friedman, a constitutional law professor at New York University.

The Sheriff’s Office has a contract with one facial recognition vendor: Clearview AI, which it pays $25,000 a year. According to documents obtained by The Times in a public records request, the department first signed a contract with Clearview in 2019.

Clearview scraped billions of photos from the public web, including social media sites, to create a face-based search engine now used by law enforcement agencies. Mr. Reid has many public photos on the web linked to his name, including on LinkedIn and Facebook. The public information office for the Jefferson Parish Sheriff’s Office did not respond to requests for comment about the use of Clearview AI.

The company’s chief executive, Hoan Ton-That, said an arrest should not be based on a facial recognition search alone.

“Even if Clearview AI came up with the initial result, that is the beginning of the investigation by law enforcement to determine, based on other factors, whether the correct person has been identified,” he said. “More than one million searches have been conducted using Clearview AI. One false arrest is one too many, and we have tremendous empathy for the person who was wrongfully accused.”

Detective Bartholomew’s identification of Mr. Reid led to a second warrant for his arrest in East Baton Rouge Parish, where, according to a police report, the man he resembled had used a stolen credit card to buy a $2,800 Chanel bag at another consignment store.

The Baton Rouge Police Department “trusted the information” from the Jefferson Parish Sheriff’s Office, a department spokesman, Sgt. L’Jean McKneely, said. “What methods they used, we do not know,” he added.

Law enforcement officers generally say they do not need to mention the use of facial recognition technology because it is only a lead in a case and not the sole reason for someone’s arrest, protecting it from exposure as if it were a confidential informant. But according to Clare Garvie, an expert on the police use of facial recognition, there are four other publicly known cases of wrongful arrests that appear to have involved little investigation beyond a face match, all involving Black men. She has come across a handful of other examples across the country, she said, in her work with the National Association of Criminal Defense Lawyers.

For Rashad Robinson, the president of Color of Change, a racial justice advocacy group, the technology exacerbates the problems of what he called “racist policing.”

“If facial recognition was misclassifying white people, white men or white women, it would not be on the shelf,” he said. “Some of us and some of our communities are expendable.”

To get a warrant to arrest someone, an officer must convince a judge there is probable cause — meaning, essentially, there is a good reason to do so — and get the judge’s signature. In the past, that meant an officer had to go to court, or even meet a judge at a diner in the middle of the night if the case was urgent. That is a moment when questions are asked about the strength of the evidence, legal experts say.

But the friction of getting a warrant has been eased by technology. The Jefferson Parish Sheriff’s Office uses an “eWarrant” service, CloudGavel, for which it paid $39,800 last year. It’s an app that allows officers to request digital signatures from judges. “Law enforcement officers can now get an arrest warrant approved in minutes,” the company’s website states.

Many civil liberties advocates actually favor electronic warrants; they allow judges to more easily review decisions made by the police and eliminate a complaint from officers that it’s too hard to get a warrant. But advocates said it would be worrisome if judges were simply clicking a button without asking questions or providing sufficient scrutiny.

“There are real questions about whether it increases the incidence of judges rubber-stamping warrants,” said Nathan Freed Wessler, a deputy director with the A.C.L.U.’s Speech, Privacy and Technology Project.

A criminal court judge signed off on Mr. Reid’s arrest warrant at 4:28 p.m. on July 18. CloudGavel “accommodates” judicial scrutiny, said Casey Roussel, the president and chief operating officer of CloudGavel’s parent company, FusionStak, in an email. He said judges could “connect with the officer via phone or video to discuss any concerns the judge may have about the warrant.”

In Mr. Reid’s case, it is unclear if the detective spoke with the judge or explained the nature of the “credible source.” The judge declined to comment.

A ‘Random Query’

“I was driving the normal speed, and I wasn’t doing anything crazy,” Mr. Reid said of the day of his arrest.

Body camera footage obtained by The Times reveals that four police vehicles were involved in pulling him over. The two warrants for his arrest asked for “full extradition.” To the law enforcement officers in Georgia, Mr. Reid would have appeared to be a fugitive from Louisiana justice.

Why exactly Mr. Reid and his white Jeep attracted the DeKalb County police’s attention that day is unclear. The arresting officer wrote in an incident report that he had learned about Mr. Reid’s warrants from a “random GCIC/NCIC query of the vehicle tag,” referring to the National Crime Information Center, an F.B.I. repository of wanted persons and vehicles, and the Georgia Crime Information Center. It’s possible the officer saw Mr. Reid driving by and, for some reason, decided to run his license plate.

But Molly Kleinman, the director of a technology policy research center at the University of Michigan, said many kinds of surveillance technologies on the highway could have alerted the officer to Mr. Reid’s presence on the “hot list,” including toll pass readers and automated license plate readers, which Atlanta has in the hundreds on roads and police vehicles. (A spokesman for the DeKalb County police said a license plate reader was not used.)

“There’s a lot of secrecy about all of these surveillance technologies and the ways that they’re used,” Ms. Kleinman said. “This case is a perfect example that even when the tool works as intended, if the underlying data is flawed it can still harm innocent people.”

Mr. Reid sat in DeKalb County jail for nearly a week. He could not be released on bond because he was supposed to be held until Louisiana officers came to pick him up for prosecution in their state. His Jeep was towed and impounded.

“Imagine you’re living your life and somewhere far away says you committed a crime,” Mr. Reid said. “And you know you’ve never been there.”

His lawyer, Mr. Calogero, gathered photos and videos of Mr. Reid from his family, hoping to more clearly show the Louisiana police what Mr. Reid looks like, and sent them to the Jefferson Parish Sheriff’s Office on Wednesday, Nov. 30, five days after the arrest. An hour later, Mr. Calogero said, an officer called to inform him that the police were withdrawing the warrant because they had noticed a mole on Mr. Reid’s face that the alleged purse thief did not have.

Mr. Reid’s detainment was “unfortunate by all means,” Sheriff Joseph P. Lopinto III of Jefferson Parish said. “As soon as we realized it wasn’t him, we moved mountains in order to get him out of jail.”

A Jefferson Parish judge recalled the warrant on Wednesday afternoon. “After further investigation, it was learned Randal Reid was not involved in the crimes committed,” the recall said. Mr. Reid was released late Thursday night, almost a full week after being pulled over. He is considering filing a wrongful-arrest lawsuit.

“Thousands of dollars for something I didn’t do,” he said.

Mr. Robinson, the Color of Change president, said most people in the United States did not have thousands of dollars to clear their names. These people will have “names and stories we will never know,” he said. “They will languish in jails and prisons.”

Alain Delaquérière and Kirsten Noyes contributed research.