Beware of fraudsters trying to dip into your wallet when you fill up with gas.

While you are paying at the pump, an thief may be secretly recording your credit card number. A Las Vegas man sentenced this week to 56 months in prison for his role in gas pump skimming fraud scheme in Nevada and Southern California that cost unsuspecting customers more than $5 million is the latest in a wave of similar schemes unfolding across the nation.

Between June 2018 and June 2022, Juan Luis Sosa Tamayo, Danyer Manuel Alarcon Rodriguez, Adrian Leyva Tamayo and Francisco Rodriguez Gonzalez put the devices fueling stations in Las Vegas and Reno, Nevada, and Bakersfield and Fresno, California, according to court documents from the U.S. Attorney’s office in Nevada. The men obtained information from at least 8,229 stolen credit and debit card numbers from the places they covertly hid the skimming devices.

Gas pump skimmers can be difficult to spot for average consumers, because most people are on the go when they buy gas and aren’t especially on the lookout for anything suspicious during a routine stop to fill up the tank. The devices are essentially a card overlay, which is a device that fits over the card terminal on the pumps and is designed to be undetected but will collect your data as you enter your PIN and complete your transaction.

Although the skimmers are designed to look like a typical credit-card slider on any gas machine, they often stick out under close scrutiny because they aren’t securely attached to the pump. Typically they are black and bulge out conspicuously, with no official markings. They may also wiggle or even come lose from the front of the pump.

Thieves may also install a hidden camera so they can capture your PIN if you pay with a debit card.

Sosa Tamayo had pleaded guilty to one count of conspiracy, one count of use of unauthorized access device, and one count of aggravated identity theft, prosecutors said. Rodriguez Gonzalez and Alarcon Rodriguez were previously sentenced to 70 months and 61 months in prison for their part in the scheme, respectively. Leyva Tamayo is awaiting sentencing later this month.