There are several signs that are good indicators of stalking behaviour. It is also important to consider the intensity of such behaviours.
1. Persistent phone calls despite being told not to contact in any form.
2. Waiting around in neighbourhood.
3. Threats.
4. Manipulative behaviour.
5. Sending written messages: letters, emails...
6. Defamation: The stalker often lies to others about the victim
7. "Objectification": The stalker derogates the victim, reducing him to an object -- this allows the stalker the ability to feel angry with the victim without experiencing empathy .... read more signs and indications here ...