Absent Without Permition

what step must the employer take if an employee was absent for 3 days at work without permission

Dear doctormabena
Welcome to CiteHR.com !!!
What do you have in mind ?? The usual and fair step is, to seek an explanation (formal/informal) for this. Perhaps the employee was sick or met with an accident. Give her an opportunity to explain.
Warm regards.

Dear Doctormabena,
As suggested by Mr.Raj Kumar it will be fair on your part to seek an explanation. But if in your opinion he is habitual in doing it, then you need to be more formal in seeking a written explanation.
If he repeats this act then you will have to build a case against him. The law of the land believes in Principles of Natural Justice. In short this means that the employee has to be given a fair opportunity to be heard before acting upon it.
Even in domestic enquiries conducted to probe into misconduct of an employee the enquiry officer generally follows this principle.
ALL THE VERY BEST!!!
M.V.KANNAN