More from the article...

... A picture of a compromised system shows how hard it is to detect. In one example, you can see a slot in the back where criminals hide a pinhole camera. The camera allows them to record you entering your PIN. ...

In addition to warning your bank of a strange charge, Nikolov recommended notifying police: "If we don't know about it, we can't hold people accountable for it." That includes a small charge, which the detective said could be a warning.

"A lot of times what these guys are doing is they're going to use the ATM and they're doing inquiries just to see how much money is in there," Nikolov said.
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How can you spot a skimming device? ...