The most frightening stalkers may be the ones who make themselves known. But the most dangerous are those who try to avoid being noticed by their targets.

The most obsessive go to extremes such as obtaining a private detective’s licence or hiring a helicopter to continue surveillance of their victims, according to a new study.

“Predatory” stalkers are often only glimpsed by their victims, who may report not being certain about being followed, but these offenders are often preparing for a sexual attack, researchers found when analysing 145 Victorian cases: “One predatory
stalker sought help having reached the point of equipping an isolated house, acquiring ether and ties and being poised to abduct the victim.”

Professor Paul Mullen, of the Victorian Institute of Forensic Mental Health, is the main author of A Study of Stalkers, which is to be published in next month’s American Journal of Psychiatry. He reports that stalkers fall into five categories.

“The rejected” stalk after a relationship breakdown, most frequently with a partner but sometimes with a mother, friend or colleague. They are motivated by a sense of loss as well as anger and vindictiveness.

“The resentful” stalk to frighten and distress the victim. Some pursue a vendetta against an individual – usually an ex-partner – while others choose targets at random: “An example was a young woman persistently pursued because she had appeared, when glimpsed in the street, to be attractive, wealthy and happy at a time when the stalker had just experienced a humiliating professional rejection.”

“The incompetent” understand that their affections are not reciprocated but hope their efforts will eventually succeed. They include intellectually and socially limited people who either have no understanding of normal courting or are unwilling to try low-key social interaction as a first step to a relationship.

“Intimacy seekers” want to be close to the object of their unwanted attentions, whom they see as their true love.

Sixty four per cent of stalkers studied had made threats and 36 per cent were “assaultative”. Threats and property damage were most frequent among the resentful, but the rejected and “the predatory” categories committed most assaults. The duration of stalking studied varied from four weeks to 20 years.

Forms of harassment included multiple telephone calls of up to 200 in 24 hours, grotesque “gifts” such as dead cats or mutilated photographs of the victim, and the ordering of unwanted services ranging from early morning pizza deliveries to emergency ambulances.

Eighty per cent of stalkers were men, 40 per cent were unemployed and more than half had never had an intimate relationship. Victims included former partners (30 per cent), professional contacts such as doctors (23 per cent), work colleagues (11 per cent) and strangers (14 per cent).

First published in The Age.