What is a defining feature of stalking under criminal law?

Stalking in the context of criminal law is characterized primarily by a pattern of behavior intended to harass, intimidate, or frighten an individual. This behavior often involves repeated and unwanted surveillance, which can create a sense of fear or distress in the victim. The correct choice highlights the aspect of actively surveilling someone with the intent to harass or intimidate, which reflects the critical element of intentionality behind stalking laws.

In contrast, being a former partner of the victim can sometimes play a role in a stalking case but does not define stalking itself. Stalking can occur regardless of the nature of the relationship. Following someone for research purposes doesn’t inherently involve malice or an intention to intimidate, which is essential for the behavior to be considered stalking. Lastly, occasionally visiting a friend's home does not constitute stalking, as it lacks the patterns of unwanted behavior or the intent to harass. Therefore, the focus on purposive surveillance aimed at causing fear or distress distinguishes stalking as defined in criminal law.