FAIRFAX COUNTY, VA -- Financial Crimes detectives from the Fairfax County Police Department are investigating several cases of skimming devices -- including three found in the Richmond Highway area -- discovered at local businesses around the county between June and October. Criminals use skimming devices to capture information from credit and debit cards. Devices were found at the following locations:

June 8: Exxon, 5211 Ox Road, Fairfax

July 22: Exxon, 6330 Multiplex Drive, Centreville

August 8: Exxon, 8021 Leesburg Pike, Vienna

August 10: Exxon, 801 Dolley Madison Boulevard, McLean

August 31: Exxon, 3403 Holly Avenue, Annandale

Sept. 16: Exxon, 6948 South Kings Highway, Alexandria

Sept. 27: Gulf Oil, 8689 Richmond Highway, Alexandria

Oct. 18, Wal-Mart, 6303 Richmond Highway, Alexandria

Police investigation shows some of the stolen credit card information was subsequently used at various ATMs to withdraw cash. Detectives are looking into whether any of these cases are linked, but suspect a number of gas stations were targeted because those locations had older-model machines that were easier to infiltrate and alter.

How does a skimming device work? A skimming device is affixed to, or installed into, a machine with a card reader, according to the Fairfax County Police Department. When you slide your card through the reader for your transaction, the device collects financial information from the card, to include PIN numbers.

Skimming devices in the 21st century are more technologically advanced. Older skimmers attach to, or cover, a machine's card reader; an accessory device is usually hidden nearby. You may be able to see loose fixtures, tape or adhesives on a machine that would draw your attention to a problem.