He told participants at the session, "In the mid-'90s, premium fraud was relatively obscure--not like it is today." Mr. Johnson also commented that many of the premium schemes "are becoming more organized-crime driven because it's an easy way to launder money."

In his biggest case to date, he said he had unmasked a $15.5 million premium theft in Indiana by a business that tried to get away with paying $471,000.

Mr. Johnson advised insurance investigators at the session that it is important for them to have top-level support when they investigate clients, an activity that may run counter to a see-no-evil attitude by some underwriters.

"If you don't have the backing of senior management, you're in trouble," he said, cautioning that speedy action is important, because "the longer you wait, you're talking millions you will never recoup."

Among the methods used by companies to dodge the payment of proper comp premium amounts, he noted, are misstating the size of payroll and employees and misclassifying workers as doing jobs with less risk attached.

The use of wrong class codes, Mr. Johnson said, is very common with construction, employee leasing and trucking firms. Other dodges involve misrepresenting the locations where workers are situated to put them in a state that charges less for their job class and incorporating the firm as a new business to avoid a poor experience rating.

Mr. Johnson detailed how businesses that are aware that insurers have certain thresholds will lie to keep their premium cost below $10,000, "so you guys don't take a look at me."

Mr. Johnson noted that premium crooks are not always "the brightest candle." In pursing them, he often simply goes on their company Web sites to see where they say they are operating and what jobs they are performing.

Mr. Johnson told of one case where the employer had changed its name to get a new experience rating but was so sloppy in their masquerade that they sent in a check for the premium with the old company's name on it.

In another instance, he said, a dishonest company changed its name using a consultant they hired to mask their activity. When the consultant stole some of their money, they sued him and outlined in their court papers their scheme to reincorporate to get a better insurance rate.

Investigators with suspicions should examine corporate tax returns, which will frequently include data not reported to the insurer, he added.

To get a true idea of a construction firm's work volume, Mr. Johnson suggested checking counties for work permits and values of jobs. He also recommended looking at Dunn & Bradstreet sales information and estimated employees.