The man was careful to wear a mask. He had more than 20 aliases and nearly as many birth dates listed by Interpol.

Rather than risk being identified via license plate, he sometimes rode a bike to the A.T.M.s and automated credit card readers he had gotten so good at skimming. He almost never stole more than $200 from any one person’s account, a move prosecutors said was most likely intended to help him evade detection.

In the end, however, his undoing may have been a short temper. He lost his cool at a rental car counter, according to court papers, ending a skimming run that prosecutors said robbed tens of thousands of dollars from hundreds of California and Alaska residents.

The federal authorities said they had identified and charged the suspect, Marcus Catalin Rosu, a 39-year-old Southern California resident and Romanian citizen, on Monday with possession of “counterfeit access device-making equipment,” according to the complaint filed in a district court in Alaska.

On July 11, Mr. Rosu attracted the interest of the airport police at Alaska’s Ted Stevens Anchorage International Airport when he arrived late returning one vehicle, and then demanded that Enterprise Rent-A-Car agents give him a different customer’s car, according to Karen Vandergaw, an assistant U. S. Attorney.

“Because they could not give him that car and the displeasure of his conduct, airport police were called,” she said in an interview.

The police soon realized Mr. Rosu was wanted in a federal investigation. On the dashboard of the car he was adamant about returning, they found a key to a hotel room. Hidden in the ceiling of that room, investigators found around 1,000 blank, gold-colored magnetic strip cards and a bag of what appeared to be A.T.M. skimming components, including a magnetic strip card encoder, the complaint said.

At a detention hearing on Thursday afternoon in Anchorage, Mr. Rosu did not enter a plea, according to his lawyer, Ben Crittenden. “We believe in his innocence,” Mr. Crittenden said, adding that his client intended to plead not guilty.

If Mr. Rosu is ultimately convicted, it would be a relatively rare win in the battle against what David Tente of the ATM Industry Association called “the biggest fraud issue” affecting his industry. Despite advances in bank card security, criminals involved in this kind of fraud have continued to find ways to compromise the banking machines.

Their techniques vary but the basic idea is that the person inserts some sort of device in an A.T.M. or credit card reader in order to rapidly capture critical information. They later use this information to make purchases or create counterfeit cards.

The people involved in skimming often operate as part of international crime syndicates. The cybersecurity writer Brian Krebs has demonstrated that some have even found ways to hack A.T.M.s wirelessly, without touching the machines.

This investigation that led to Mr. Rosu’s arrest began in February, when U.S. Postal Inspection Service employees became suspicious of a package en route from Santa Ana, Calif., to a hotel in Palmer, Alaska, according to the complaint. Inside the parcel, inspectors found 555 gold magnetic cards bundled into groups. Alexander Laumb of the Seattle Division of the U.S. Postal Inspection Service began to try to piece together what was going on.

By March, Mr. Rosu, who was arrested in Australia in 2010 in a similar case, had become a focus of the investigation. Mr. Laumb learned that Mr. Rosu was caught trying to install a skimming device at a credit union in Groton Town, Conn. in October 2019 and that he had a history of skimming in other parts of the United States and the United Kingdom, according to the criminal complaint.

Mr. Rosu’s bank account showed that though he lived in Southern California, he made frequent “cashout” trips to Anchorage, according to charging documents. Ms. Vandergaw declined to offer specifics of how his system worked, but the complaint suggests that on these trips he would make dozens of small deposits using counterfeit cards he had encoded with data gleaned from his skimmer.

From August 2019 to March 2020, he deposited more than $180,000 this way, the complaint said. Back in California, he would withdraw the money, according to court papers.

Though inspectors had developed this theory, they had a problem: how to locate Mr. Rosu. And that’s where Enterprise Rent-A-Car came in. According to a police report, on a Saturday afternoon a week ago, a man was “becoming aggressive toward an Enterprise agent.”

During questioning, the airport police realized this was a man sought by federal agents. When investigators searched the rental truck, they found a bicycle, one that had recently become familiar to inspectors. On July 9, an employee of a credit union in Willow, Alaska, found it suspicious that a customer would visit that part of town without a car. The employee photographed the bike, according to the complaint. Later, a skimming device was found on the premises.

Mr. Rosu is currently in jail in Anchorage waiting for a bail hearing.

Seamus Hughes contributed research.