-Certain protections given in a criminal or civil matter don't apply in an employer/employee setting, especially when there is an express "duty to cooperate" clause as a part of the employment agreement(s). Many employees, for instance, might try to plead the 5th, and that might work as far as a criminal investigation or often in a civil suit, but it doesn't work too well against an employer. "Talk or walk" is the common catchphrase many times.
I don't know if people realize how much effect the duty to cooperate clause has on this matter.