SEATTLE, Wash. -

They target the most vulnerable, but there is one sure way to avoid being their next victim.  It's something Louise Mueller wishes she knew.

“I was kind of worried about my income, my finances, and how I was going to make it,” said the 84-year-old.

Mueller had just become a widow, her son was serving in Iraq and she needed to return to work.  She admits she was overwhelmed .  Then she received a phone call.

“He said I won a sweepstakes,” Mueller explained.

She was told she needed to pay $2500 in taxes in order to receive her $250,000 prize. So, she did. But no prize ever arrived. The phone rang again.

"I did keep saying to them, 'Where is my money, where is my money?' And they said, 'Well, I'll tell you what, we'll meet you at the bank.' I was at the bank. They were not," Mueller explained.

"If you're receiving phone calls telling you need to send money in order to collect winnings. Most likely you are being scammed," warned US Postal Inspector Frank Schissler.

"They kept calling and calling and calling. One time they called 17 times in 10 minutes," said Mueller.

She lost $20,000 and knows why she was vulnerable.

"I was sad, I was grieving, and I needed the money. So, I kind of fell for it," she admitted.

Postal inspectors say con artists prey on the victim's emotions. All consumers need to remember is this:

"No legitimate lottery or sweepstakes will ask you to send money, wire money or pay any kind of taxes, fees or other types of payment up front in order to collect your winnings," Schissler said.

Postal inspectors says approximately 30,000 calls are made from Jamaica into the US every day, attempting to defraud American citizens.