A man on a local S train headed toward Copenhagen early on Sunday morning stood up and masturbated in front of a woman riding in the same car.
The woman got off the train at Farum Station and told police about the offensive flute solo she had just been forced to witness.
Police then managed to pull him off at Hareskov Station, where they arrested him, according to Frederiksborg Amts Avis.
Abusing himself and others for years
The 28-year-old man from Farum was arrested and taken to the station where police discovered that this was not the first time he had subjected unsuspecting women to his machinations.
They now suspect him to be guilty of as many as 20 cases, and he was held over to appear before a judge.