An elderly woman was seen clutching a "CRA Legal Notice" and feeding a large amount of cash into a Bitcoin ATM in a local convenience store on Thursday.

Someone else in the store noticed what was going on and called police, believing her to be the victim of a scam.

Hamilton police showed up and answered the woman's phone when it rang.

The scammer went as far as masking his or her own phone number, and it appeared on the woman's phone like the number of the person calling was 905-546-4925 – the non-emergency line of the Hamilton police. The person on the other end of the phone said she was "Mary Jones" of Hamilton police.

Police found out that the woman had deposited almost $17,000 into Bitcoin machines in the area in a matter of days, said Det. Sgt. Greg Doerr, who oversees the police major fraud unit.

"The reality is that it's going to be a very hard investigation," Doerr said. "Once you transfer money into Bitcoin it's very hard to track where it went."

Often embarrassment about being contacted by the CRA or the government keeps people from telling their families – but even just asking someone else if the letter seemed legit might have saved this woman from the scam.

"Nobody believes they will ever fall victim to such a scam but many people do," police remind in a press release about the incident.

"Some people are more susceptible to deceptive tactics and we need to make sure they are aware of these fraudsters."

They emphasize that no official government or administrative centre will ever ask you to pay using Bitcoin ATM, iTunes or Steam cards, other prepaid gift cards, or wired money through Western Union.

They also won't text you or use as intimidating and "high-pressure" tactics, police say.

Doerr said police will be tracing the calls and emails that the woman received and trying to find a lead on the investigation. But he emphasized that the more people who know about these scams happening, the less likely they are to succeed.