I just read an article about an attorney who applied for a position and was disbarred for misrepresenting information on her resume. It seems that the attorney's immediate prior employer was her husband. She did not explain this on her resume, nor did he disclose that she was married to her boss, despite the fact that she used her husband's letter recommendation in support of applying for the position. This scenario shows you that you never know who you are interviewing or how accurate references or resumes are that are submitted to your company.
I have a client that never calls the reference on a resume; they call the supervisor of the employment reference. After all, who is going to provide a reference to someone that's going to say something negative about the applicant?
Also, after making an offer to someone, it's a good idea to conduct a criminal background, credit check (particularly if the position involves A/P, accounting or finance) and to verify employment. I defending a recent employment discrimination case, a plaintiff completely omitted an employer on her resume for employment after leaving my client's employ. Further, in inquiring further, we learned that the person had mispresented her educational background, including claiming to have earned a degree from a particular university. All it took was a call to the registrar's office to learn that they had no record of the person having graduated.
Ask yourself: if a person would lie about their education or employment history to get this job, what would he or she billing willing to lie about to keep this job?