Your security concerns with an employee should not stop after that person is hired.
Every potential computer user should undergo fundamental education in security policy as a matter of course. At the least, this education should include procedures for password selection and use, physical access to computers and networks (who is authorized to connect equipment, and how), backup procedures, dial-in policies, and policies for divulging information over the telephone. Executives should not be excluded from these classes because of their status—they are as likely (or more likely) as other personnel to pick poor passwords and commit other errors. They, too, must demonstrate their commitment to security: security consciousness flows from the top down, not the other way.
Education should include written materials and a copy of the computer-use policy. The education should include discussion of appropriate and inappropriate use of the computers and networks, personal use of computing equipment (during and after hours), policies on ownership and use of electronic mail, and policies on import and export of software and data. Penalties for violations of these policies should also be detailed.
All users should sign a form acknowledging the receipt of this information, and their acceptance of its restrictions. These forms should be retained. Later, if any question arises as to whether the employee was given prior warning about what was allowed, there will be proof. ...