The Aurora Police Department is investigating two cases of ATM skimmers being found by Old Second Bank employees in the 1300 block of North Farnsworth Avenue and the 4000 block of Fox Valley Center Drive.

The skimmers are used by criminals to steal credit card, debit card and PIN numbers.

The first skimmer was located around 6:30 a.m. Saturday, Sept. 22, at the Farnsworth branch after an alert employee reporting for work saw a woman walk up to the ATM and began acting suspiciously.

After the woman walked away from the machine and left the area, the employee checked the ATM and located the skimmer. The bank then notified personnel at its other branches and a short time later, a skimmer was found at the Fox Valley Branch.

It is not known for certain if any accounts were compromised.

“Our detectives are currently looking through security videos as part of the ongoing investigation, and we will release more information as it becomes available,” said Dan Ferrelli of the Aurora Police Department. “There is a high probability that the incidents are related. We’re reminding you of the importance of inspecting ATM machines for these types of devices before you use them.”

Here’s how skimming devices work:

The skimmer grabs data from the magnetic stripes of credit and debit cards every time they are swiped, giving a criminal plenty of information he or she can use to clone card numbers or break into bank accounts and steal money.

The skimmer, which is smaller than a deck of cards, is designed to easily slip over the machine’s actual card reader. The pinhole camera can be incorporated into the skimmer, on top of the ATM or just to the side inside a plastic case that may contain brochures or other materials.

ATM skimmer suspects, vehicle. (CREDIT: APD Facebook page)

The skimmer then captures PIN numbers as they are inputted by the ATM user. Fake number pads installed over the actual keyboards that record the PIN numbers as they are entered have also been used, which negates the need for the tiny pinhole cameras.

So, what can you do to help make sure your information is not stolen?

Check for tampering on the ATM (or credit card reader) before you begin your transaction. Look at the top of the machine, near the speakers, the side of the screen, card reader or keypad.

Do you see any obvious signs including different colors or materials? Maybe the graphics don’t line up? Something does not look like it fits properly in the machine? Do the card reader, keyboard, or other parts of the machine move when you touch them?

If something doesn’t seem right, don’t use that machine and call the police.

When you enter your PIN, assume someone is always looking —whether over your shoulder, or with a pinhole camera. Cover the keyboard with your hand when you input your PIN.

If your information does get stolen, remember to report it to your bank and debit/credit card company. Keep close watch over your accounts also, because time is of the essence if you are victimized.

Remember, too, that banks and credit card companies have very rigorous fraud detection policies and will immediately reach out to you at the first sign of something suspicious.

Further information on how to keep your transactions secure is available from your financial institution or debit/credit card company, the Federal Trade Commission and the various credit bureaus.