Allow the student to examine your evidence.
Explain what you suspect and why.
Give the student an opportunity to respond. S/he may be able to provide a plausible explanation. On the other hand, this may be an opportunity for a student who would like to take responsibility for the offence to do so.
Be prepared for possible false excuses, but open-minded enough to consider plausible explanations.
If, at the end of the meeting, you believe there was a Code violation, advise the student that you are required to turn the case over to the Dean of the Faculty and that you do not have the discretion to impose any sanctions on your own. You may wish to provide reasons for this: it maintains consistency across the Faculty and provides the opportunity for appeal. It also allows the University to track students who have violated the Code in other departments or Faculties.
If you are planning to send the case to the Dean, let the student know that the Dean’s office will contact him or her to make an appointment.
Avoid threatening to send the evidence to the Dean if the student doesn't confess. You are required to send the case on to the Dean any time you suspect a Code violation, whether or not the student has admitted to it.
Do not take matters into your own hands and simply assign a zero on the paper. Our system is based on natural justice, which accords certain rights before any sanction is imposed. If you assign a zero on the paper without sending the information on to the Dean, not only are you acting without proper authority, but you are depriving the student of any right to appeal. You could also be laying the groundwork for a valid grade appeal and allowing serial cheaters to continue undetected.