Retrieving Company Property
You would be well advised to include in the employment contract a provision that when an employee leaves (particularly an employee with access to confidential company information) he must return to you all your possessions, including any documentation and any copies he has made.
If you suspect that equipment, records or other possessions belonging to you have not all been returned by the outgoing employee (especially if that employee is likely to be in a competitive position and that materials may be used to your detriment) you can apply for a search order whereby his or other relevant premises will be searched.
This is a drastic remedy for use in situations where documentation and other evidence is likely to be destroyed or misused, and where the impact on your business caused by the misappropriation of such documentation or materials is likely to be significant. Such a provision may well be effective support for other provisions which restrict competitive activities by ex-employees.