In October, an accountant at 321 Takeoff Inc. in New York became suspicious after an employee who normally filed weekly expense reports for around $80 began requesting $120.

When Alona Fromberg-Elkayam, the branding agency's president, approached the employee, she says she was met with flimsy excuses. She fired the employee, a midlevel designer.

In the wake of the recession, more businesses are facing a growing financial threat: employee theft. New research shows that employers are seeing an increase in internal crimes, ranging from fictitious sales transactions and illegal kickbacks to the theft of office equipment and retail products meant for sale to customers.

Employers suspect that workers are pilfering from them to cope with financial difficulties at home or in anticipation of being laid off.

What's more, it's often the most trusted workers who are committing the thefts.