Detectives watching surveillance videos of car break-ins across the country have noticed an alarming trend: thieves opening locked doors as if they had an electronic remote.
It turns out they do.
Hackers have perfected several types of electronic gadgets that can unlock car doors, experts said.
In Watauga last year, officers arrested two car thieves with one of the devices, police said.
"Basically they use it to try to mimic the signal that your key fob sends to your car to tell it 'unlock your doors,'" said Arlington police Detective Jesse Minton, an investigator with the Tarrant Regional Auto Crimes Task Force.
It works by going through millions of codes until it gets the right one, experts said.
And there are other electronic techniques crooks are now using.
One involves a so-called "power amplifier" which boosts a remote's signal. So even if your key is safely inside your house, the signal is greatly amplified and fools a car's security system.
"The car thinks the key is closer than it really is," said security expert Jeff Zisner of Aegis Security in Los Angeles.
Thieves can then open the door as if they had the key with them.
Most devices won't allow thieves to start your car, only unlock the doors.
But in Washington, researchers revealed another way thieves can clone keys to certain high-end cars.
"The only scenarios of concern are in situations where somebody you don't know or don't trust have access to your key," said Flavio Garcia of the University of Birmingham in the United Kingdom.
Once the key is copied, he said, a thief could actually start your car and drive away.
In some California neighborhoods hard hit by the "power amplifier" scheme, people are actually putting their keys in microwaves or refrigerators to cut off the signal.
But with thieves now armed with so many electronic tricks, police in North Texas say the solution to the high-tech crime is common sense.
"The best thing to do is just do not leave valuables in your car," Minton said.