The beautiful teen, who had gone missing some time in the early hours of June 4, 1990, on her way home from a party amid Copenhagen’s Pentecost celebrations, was found dead in the basement of her apartment block building in the neighbourhood of Teglgårdsstræde.

Anne’s hands and neck had been tied up with cord attached to the door handle so she would be strangled if she moved; two dishcloths had been put in her mouth and her body covered with floor wax. A symbol that looked like “PK” was etched into the skin of her right forearm.

Anne Stine Geisler Image: Supplied

She was found by a chef working for a restaurant housed in the building’s ground floor.

A new book about the murder case, En Djaevel I Den Lyse Nat (A Devil in the Bright Night), reveals how the Crown Prince was deeply shaken when he received the awful news of Anne’s death.

She was known by friends and family as a happy girl, and Frederik would bump into her daily in the halls or stairways of the prestigious Krebs School, which they both attended until their early teens when they graduated on to different high schools.

Located in the leafy, mostly residential Stockholmsgade district, Krebs is a private school popular with the upper class and royals.

Although Frederik was four years older than Anne, he still remembered his time at school with her and, according to the book’s author, Danish journalist Soren Baastrup, he was enormously emotionally affected by her death.

The murder has haunted Fred. Image: Getty

In a strange twist of fate, her father, Steen Geisler, had also been Prince Frederik’s maths teacher.

Several men were questioned in connection with Anne’s death. One was a 40-year-old journalist who was married but allegedly had an affair with the teenager. He was later found to have a watertight alibi for the night of Anne’s death.

Another suspect was a man in his early 30s who Anne was seen arguing with at a nearby bar. Police came to believe this man was in love with Anne. He was described by people who knew him as “unpleasant” and “horrible” but no evidence was ever found to link him with the teenager’s death.

Another suspect, already known to police as a dangerous criminal, was a man with the initials PK: Peter Kronholm. Also known as Mr Smiley, he was seen at a cafe a few metres from the basement where Anne’s body was found, but no other evidence to link him to her killing was ever found.

Three years later he was imprisoned after murdering his stockbroker girlfriend and he remains locked up to this day.

Another man questioned by police was Jakob Illeborg who, like Anne, was a student at the high school Christianshavns Gymnasium. They were in the same music class but while Jakob was questioned by the police shortly after Stine was killed, he was cleared of her murder.

In his book, Baastrup suggests a connection to similar crimes around Copenhagen at the time, in particular those carried out by serial killer and rapist Marcel Lychau Hansen.

He points out that Hansen – who is currently in prison serving a life sentence – used the similar neck to wrist technique of tying up his victims.

After the death of his childhood friend, Prince Frederik sent a personal letter of condolence to her family: Kirsten and Steen Geisler and Anne’s 14-year-old younger brother.

Kirsten, who still lives in the building where Anne was found, says she hasn’t been down to the basement since the discovery of her daughter’s body.

“She was a shining creature. She was fun-loving and with a huge interest in the outside world,” she says. “I still don’t understand who could hurt my beloved daughter.”

This story originally appeared in New Idea and was written by Milly Haddrick