One lesson of the financial meltdown is that if regulators aren't looking for fraud, they aren't going to find it. And they still aren't looking.

The defining characteristic of crony capitalism is the ability of favored elites to loot with impunity and the failure of regulators to do their jobs.

We have seen this in the financial crisis that started in 2008 and in an earlier era, when the savings-and-loan industry collapsed.

In the Texas "Rent-a-Bank" scandal of the 1970s, for example, two ringleaders created a fraud network of 50 lenders that caused billions of dollars in losses. The watchdogs removed and sanctioned one of the main culprits, but because the crimes weren't prosecuted, the same crooks reappeared in the 1980s to do it all over again, only on a bigger scale. Unless you imprison the fraudsters, sophisticated financial scams grow ever more destructive.

It seems as if we have forgotten this lesson.

Take the seven senior officials convicted in the failure of one of the lenders that drove the 2008 credit crunch. All of the cases arose from an investigation of Taylor Bean & Whitaker Mortgage. The first trial occurred earlier this spring -- 6 1/2 years after the FBI warned publicly that there was an "epidemic" of mortgage fraud and predicted that it would cause a financial crisis if it weren't contained. The trial and conviction of Taylor Bean's former chairman, Lee Farkas, occurred nine years after his crimes were suspected.

Taylor Bean was a small Florida mortgage broker before the fraud began as the housing boom took off. Fannie Mae had cited Farkas for multiple violations but had never filed a criminal referral, which would have triggered an investigation. Had it done so, Farkas might have been prosecuted and Taylor Bean shut long before it caused so much damage. Instead, it expanded, then failed, pulling down a bank with it at a cost of $2.8 billion to the Federal Deposit Insurance Corp. Farkas plans to appeal the verdict.

The Office of Thrift Supervision, the successor to the S&L regulator where I worked, made no criminal referrals in the latest crisis. The Office of the Comptroller of the Currency and the Federal Reserve made less than a handful. Mortgage and investment banks also made very few referrals -- and never against their senior officers.

While it is true that banks made thousands of criminal referrals, almost all involved low-level figures. The volume overwhelmed the FBI, which failed to devote adequate resources. As late as 2007, the agency assigned only 120 investigators spread among 56 field offices to probe thousands of cases. More than eight times that number probed the S&L frauds, a far smaller epidemic.

Unlike the S&L debacle, there was no national task force and no comprehensive prioritization. This made it difficult to investigate the huge, fraudulent subprime lenders. And because there were no criminal referrals of these firms, the FBI wasn't even attempting to pursue them.

The two great lessons to draw from this epidemic of fraud are that if you don't look for it, you don't find it, and that wherever you do look, you do find fraud.

The FBI was concentrating on retail banking, or individual borrowers and smaller lenders. But the big problems were being created in the wholesale end of the business, where loans were pooled, packaged, sold and securitized. Because the FBI looked at only relatively small cases, it found only relatively small frauds.

The FBI has been processing no more than 2,000 mortgage-fraud cases a year. There are two things to consider, though: Not only were they the wrong cases to focus on, but they amounted to nothing in light of the estimated 1 million fraudulent mortgages made annually during the housing bubble years.

The FBI -- deserted by the banking regulators and undercut by the Justice Department -- was so desperate that it formed a partnership with the Mortgage Bankers Association in 2007. The trade association had created an absurd definition of mortgage fraud under which accounting frauds by a lender were impossible and bankers were the victims. By 2009 the financial crisis had become so acute that Treasury Secretary Timothy Geithner discouraged criminal investigations of the large nonprime lenders.

Loot the bank and walk away

Nobel laureate George Akerlof and Paul Romer wrote a classic article in 1993. The title captured their findings: "Looting: the Economic Underworld of Bankruptcy for Profit." Akerlof and Romer explained how bank CEOs can use accounting fraud to create a "sure thing" in the form of record short-term income, generated by making low-quality loans at a premium yield while making only minimal reserve allowances for losses.

While it lasts, this fictional income allows the chief executive officer to loot the bank, which then fails, and walk away wealthy.

In criminology, we call these accounting-control frauds, and we know that they destroy wealth at a prodigious rate. There's no "if" about the losses -- the only questions are when they will hit, how big they will be and who will bear them.

The record income produced explains why those involved get away with it for years. Private markets don't discipline companies reporting record profits. They compete to fund them. Fraudulent CEOs can control the hiring and firing and can create the perverse incentives that produce a dynamic in which bad ethics drive good ethics out of the marketplace.

Sophisticated accounting-control frauds not only sucked in employees who should have known better, but also loan brokers. The result is that the large fraudulent lenders -- those making a lot from liar's loans -- produced an echo epidemic of deception.

Fraud, it turns out, begets fraud.