The Florida Lottery is looking for payback today, after four people were arrested in the last 48 hours on charges ranging from dealing with stolen property to grand theft.

The arrests were part of a sweeping investigation of nearly 100 Florida retailers for possible lottery fraud after it was found that, out of the top 10 winners in scratch-off games in the state, nine were convenience store owners.

Watch: Lottery scratch-off scandal in Florida.

Richard Lustig, who wrote a best-selling book after winning the Florida Lottery, said there were three quick ways store owners and clerks seemed to be gaming the system.

"They're watching people buy tickets," Lustig said. "[They see] a bunch of losers. They feel that that game has a winner coming up. No. 2 mostly involves preying on the elderly. They come in, they hand the clerk their ticket and say, 'Could you check it for me and see if it's a winner?' They tell the person, 'No, it's not.' The person walks out of the store and, in reality, the person has a $1,000 winner. So the clerk pockets it and cashes it in.

"The third way is [that] a person in the United States illegally wins a big prize," he said. "They don't want to cash it in because they're afraid of the publicity, that they're going to be caught and shipped out, so they make a deal with the store owner or the merchant."

After an ABC News report two weeks ago and other reports by ABC News affiliate WFTS-TV in Tampa, the Florida lottery zipped out a batch of public service announcements. The PSAs encouraged people to sign the tickets so that no one else could claim them.

Some clerks around the country recently have been caught playing their customers.

In Syracuse, New York, a clerk was convicted of swindling a customer, telling him that he had a $5,000 ticket when it was actually worth $5 million.

Experts said lottery players should not give a ticket to a clerk. If you wait a couple of seconds, a scratch-off machine will tell you if you've won. Lustig also suggested going to the lottery's website and checking your ticket or calling the state lottery's number.

ABC News' Matt Gutman and Maggy Patrick contributed to this story.