Victims are often familiar with their stalkers. Satu Hytönen, a student at the University of Helsinki, says she was stalked by an acquaintance for two years.

A male acquaintance began sending her inappropriate text messages. Hytönen also began receiving phone calls with heavy breathing at the other end of the line.

She notified the police after receiving text messages with images of the man’s genitals.

Authorities are often unsure of how to deal with these types of cases.

Researcher Katja Björklund says victims are often more likely to reach out to friends or relatives than the police. Her study suggests that victims are typically women.

Stalkers harass their victims for ten months on average, sometimes threatening to hurt them.