A Melbourne businessman has admitted stalking a woman with whom he had previously had a secret workplace affair, after what prosecutors described as a sustained and frightening campaign of harassment following their split. The case matters because it shows how stalking can escalate across multiple settings, including travel, hotels and surveillance, leaving the victim feeling fearful and unsafe.

Karl Mentzer, 39, pleaded guilty in Melbourne Magistrates' Court after allegedly following the woman interstate, turning up at airports and near her home, repeatedly contacting her, and threatening to "ruin" her life. The court heard he arranged hotel rooms next to hers, set up a pinhole camera facing a hotel hallway, and hired a private investigator using false claims that he was her partner; he has spent 65 days in custody. Charges linked to illegal surveillance and harassing communications were dropped, while the court was told Mentzer had longstanding cocaine and alcohol problems; sentencing was adjourned for a victim impact statement and assessment for a community corrections order.