As might be expected when the subject is security, neither Wachovia nor Bank of America are willing to explain in detail efforts they take to protect sensitive data from employees who want to illegally sell private account information.

"All of our associates must adhere to a code of ethics and to company policy," said Tara Burke, a spokeswoman for Bank of America. "And our bank associates only have access to the information they need to provide service to our customers."

The bank does perform criminal background checks on all new employees, using fingerprinting and other screening methods. Contract labor suppliers must perform criminal checks on temporary employees they supply to the bank, she said.

But the problem with background checks is that they don't work, said Jim Stickley, chief technology officer at TraceSecurity, a Baton Rouge, La.-based security company.

"Sure, (it works) if you are looking at a murderer or someone with a criminal record. But there are a million idiots out there who are lucky so they don't have a record," he said. "No matter what you do, all it takes is one person who is down on his luck or realizes he can make a lot of money doing this. Then you have your biggest nightmare."

In all, Burke said, Bank of America spends about $250 million annually on various security measures and protections, and has hundreds of associates whose sole function is to protect information.

Wachovia spokeswoman Christy Phillips said the bank employs similar protections, including offering programs and training to educate employees how to safeguard information. Background screening is a longtime policy at Wachovia and there are tools and procedures that limit access to information to employees whose jobs require such access.

"We routinely review our processes and make changes as appropriate," she said.

Among the other difficulties the banks face when working with employees, Roop said, is a high level of turnover.

"These banks hire hundreds of new people every month," Roop said.

Among the steps banks can take to fight insider ID theft is to individually limit each employee's access to customer information, Litan said. Such a system specifies exactly what customer information each employee can see, touch and update.

But that also requires managers to constantly monitor the clearance levels of thousands of individual employees.

Another way to police insider theft is "the intimidation factor," Stickley said. While some workers might complain that their rights are being infringed by aggressive monitoring of their work activities, Stickley said they need to understand "they are dealing with extremely confidential information that can wreck a lot of peoples' lives."

And at the office, Litan said, bank employees working with sensitive information know that aggressive security comes with the job.

"Their phone conversation are recorded all the time," she said. "They know there are no rights when it comes to private business."

But in the end, even the experts said protecting sensitive information from insiders comes down to basic human honesty.

"If someone wants to do it, they are going to do it," Stickley said.