The phone call last year sent Tony into a panic. Someone posing as his teenaged granddaughter was calling from Canada, saying border agents had detained her after she had spent too much money in the country. She needed her grandfather to wire $2,000 to a nearby Wal-Mart, so she could pay a fine and get back in the United States. Then someone claiming to be from the Canadian border patrol called Tony. "I was fooled right up to that point," he recalled. But he had the presence of mind to ask for a call-back number. That one rang and rang and rang. Tony knew then that he had almost been scammed. He still doesn't know how the would-be thieves got his granddaughter's name.

The "grandparent scam" is once again victimizing seniors across North America, the Better Business Bureau announced last week. Scammers succeeded in stealing $19,000 from an elderly St. Croix County, Wis., couple who wired the money in November after learning that their "grandson" had been in a car accident in Canada. The BBB cites statistics from the Canadian Anti-Fraud Call Centre showing 278 reports of failed and 88 reports of successful grandparent scams in the first 10 months of last year, totaling $317,732.63, but that number is likely 5 percent of the actual total of cases.

Tony is not easily drawn into a scam, but he said this fraud is "dangerous" because "they prey on your emotions."

Whistleblower is always impressed with the malevolent creativity of con artists. What's the most insidious one you've come across?