The Delaware U.S. attorney on Thursday revealed a massive insider data breach at chemicals company DuPont where a former scientist late last year pleaded guilty to trying to steal $400 million worth of company trade secrets. He now faces up to a decade in prison, a fine of $250,000, and restitution when sentenced in March.

Gary Min worked as a research chemist for DuPont for 10 years before accepting a job with DuPont competitor Victrex in Asia in October 2005. Between August and December of that year, Min downloaded 22,000 sensitive documents and viewed 16,706 more in DuPont's electronic library, making him the most active user of that database in the company, according to prosecutors.

It's unclear whether Min's frequent access to that database tipped off an automatic alert to DuPont officials or whether his behavior was discovered by studying database access logs. Regardless, Min left DuPont in December 2005, and after starting work for Victrex in February 2006, transferred 180 DuPont documents to a Victrex-owned laptop computer.

After DuPont discovered that Min had helped himself to a large volume of confidential and proprietary DuPont technical information, it notified the FBI and the Commerce Department. Min's Victrex computer was seized on Feb. 8, 2006, while he was at a meeting with Victrex officials in Geneva. The confiscated computer was turned over to DuPont, which in turn gave it to the FBI, according to prosecutors.

Investigators told DuPont that they haven't found any evidence that Min had actually turned the stolen information over to any of his new colleagues, DuPont senior VP and general counsel Stacey Mobley said in a statement.

Min's actions have landed him in a lot of trouble, but his case is hardly unique. "I've researched a bunch of cases where designers and scientists tend to view their company's intellectual property as their own, something they've created and something they want to take with them," says Dr. Eric Shaw, a clinical psychologist and former CIA intelligence officer who for the past two decades has studied insider threats. "As a result, they'll often ignore nondisclosure agreements and other intellectual-property mechanisms."

While many companies worry about departed employees stealing intellectual property through some sort of back door planted in their IT systems, 75% of the 40 proprietary and confidential information thefts studied between 1996 and 2002 by Carnegie Mellon's CERT program in a July 2006 study were committed by current employees, says Dawn Cappelli, a senior member of the technical staff at the CERT program at Carnegie Mellon's Software Engineering Institute. Of those current employees committing intellectual property thefts, 45% had already accepted a job offer with another company. "In between the time they have another offer and the time they leave is when they take the information," she says.

The best way to guard against insider breaches is for companies to monitor database and network access for unusual activity and set thresholds that represent acceptable use for different users. If an employee starts downloading thousands of documents, and this is unusual for the job designation, this should automatically trip red flags to an administrator or manager.

Another important measure is for companies to do account audits to make sure there aren't accounts for employees who don't exist or who no longer work for the company, Cappelli says, adding, "Companies should know all of the accounts their employees have access to."

Editor's note: This story was modified Feb. 16 to more accurately describe when Min left DuPont and joined Victrex.