Last year, law enforcement officials found more than a thousand gas pumps nationwide that had been fitted with “skimmers” — electronic devices that record credit card numbers and, in some cases, transmit them wirelessly over Bluetooth to a criminal’s computer.

This could have serious financial consequences for gas stations starting next year, when a law will require them to either spend thousands of dollars to install pumps that read the more-secure chips in credit cards or be liable for fraudulent charges. A new smartphone application could help law enforcement find skimmers before they cause too much damage.