Cloned key fobs and antennas are powering a new wave of car thefts in U.S.

Gone are the days when car thieves would hot-wire vehicles or hack ignitions with a screwdriver and a USB cable. Now, crooks are relying on antennas and cloned key fobs to steal vehicles and resell them for significant profits.

Police said thieves, often standing outside a victim’s home, use handheld antennas to trick an engine into starting by hijacking the signal between the vehicle and its key fob.

Once the engine is running, the thieves plug a key programmer into the vehicle, allowing it to learn to recognize the replacement key fob instead of its original mechanism, authorities said.

“These are tools that locksmiths use, but criminals learned how to use it, and now they’re starting up cars and stealing cars with it,” said Tom Burke, a former New York Police Department detective who specialized in auto theft cases.

These auto thefts are unlike the Kia Boyz trend that exploded during the COVID-19 pandemic emergency, when juveniles took older model Hyundais and Kias on joy rides, the veteran investigator said.

Mr. Burke said organized crime groups are behind key fob thefts coast to coast.

He said the thieves have institutional knowledge, primarily gained from prison, that enables them to scrub a vehicle identification number and produce counterfeit vehicle history reports and title documents.

Last month, law enforcement in suburban St. Louis broke up a theft ring that was cloning key fobs for souped-up muscle cars such as Dodge Chargers and Challengers.

“These thieves are going for the expensive vehicles,” St. Charles, Missouri, Police Lt. Daniel Gibbons told KTVI. “And they’re trying to sell them, so these vehicles are quickly sent out of state, or they’re stripped.”

Lt. Gibbons said the criminals can move a vehicle or chop it for parts in roughly two days.

Charging documents said the thieves stole 40 vehicles. Police recovered 21 of them.

Authorities didn’t disclose how many people were arrested in the thefts but said five were linked to crimes such as murder, assault and gun possession.

A man charged with stealing a Jeep Grand Cherokee Trackhawk outside a Milwaukee hotel this summer was linked to a sprawling theft operation.

Police told WISN-TV that they tracked the vehicle to the home of Justin Powell. They said they found more than 15 key fobs associated with various cars, as well as two key programmers, inside the residence.

Mr. Powell also faces gun and drug charges.

Some thieves are syncing cloned key fobs on the spot.

In May, prosecutors in Queens, New York, charged 20 people in the thefts of more than 120 cars that were procured by breaking out windows and hooking up a key programmer within seconds.

Prosecutors said the thieves quickly sold the vehicles — including BMWs, Land Rovers and Mercedes-Benzes — to associates in New York and Tennessee.

“This is one of the most prolific and organized auto theft rings we have ever uncovered in New York City,” District Attorney Melinda Katz said. “With these indictments, we have dismantled a criminal enterprise that stole at least $4.6 million worth of vehicles from our streets and driveways.”

Mr. Burke said stolen vehicles are often not seen again until they are listed for sale online, sometimes in foreign countries.

Africa is a prime market for stolen cars, he said, but criminals typically sell their loot in areas where they have roots.

Mr. Burke said a Chinese transnational crime syndicate called the Triads was stealing Audi A6s and shipping them back to their country.

He said an Audi model that sold for about $30,000 in the U.S. was sold for more than $100,000 in China.

“There’s more money made in the stolen car industry than there is in drugs,” Mr. Burke said.

Simple math has led organized crime groups to cloning key fobs.

Kelley Blue Book lists the average price of a new car at about $50,000, the former detective said, while a kilogram of heroin nets only $35,000 on the street.

Additionally, the legal risk associated with vehicle theft is lower.

Mr. Burke said a drug conviction could quickly lead to serious prison time, but being caught with a stolen car, especially for juveniles, typically results in lenient punishment.

“They’re getting cut loose, so there’s the problem,” he said. “The stolen car theft is out of control because of the money — the money’s there.”