INDIANAPOLIS, Indiana -

How could it happen? How could one employee steal hundreds of thousands of dollars from a company?  U.S. postal inspectors warn it can happen anywhere, if businesses don't protect themselves.

One example is Frake's Engineering.

"Brenda Helpling was a 20-year employee. She was the controller, so she controlled the finances and the bills for the company," explained U.S. Postal Inspector Kenneth Miller.

Miller says that was the problem. Helpling was the only person overseeing company finances, which made it easy for her to steal. Total losses were $400,000.

"She created fictitious accounts in order to pay her own bills and gambling expenses," added Miller.

The company realized there was a problem when Helpling went on vacation and another employee noticed discrepancies.

Miller said, "Her back-up was looking at some of the payments and she looked at the bills and realized a lot of the bills weren't companies they did business with."

The company went to police and Postal Inspectors, who say Helpling's gambling problem helped them track her down.

"We followed the money trail and it led to Brenda Helpling, and her accounts and we also went to the casinos and looked at her credit card payments," said Miller.

Postal Inspectors advise all business owners to get an annual audit done by an outside accounting firm.

"A company should always have checks and balances in place and not one person. Always check to see where money is going," warned Miller.

Helpling was sentenced to more than two years in federal prison on mail fraud charges and was ordered to pay more than $400,000 in restitution.