Peter Madsen — the inventor who became a murderer

Who was Peter Madsen?

Peter Langkjær Madsen was born on 12 January 1971 in Albertslund, west of Copenhagen. He grew up as the youngest child in a family where his father was considerably older than his mother, and by Madsen's own account his relationship with his father was fraught with conflict. From an early age he showed a pronounced fascination with rockets, engines and mechanics — an interest that would later come to define his public image.

Without any formal engineering qualifications, Madsen managed to build a reputation as a self-taught inventor. He designed and constructed three privately built submarines, of which [UC3 Nautilus](/tags/uc3-nautilus), completed in 2008, was the largest. He was a co-founder of [Copenhagen Suborbitals](/tags/copenhagen-suborbitals), a volunteer organisation with ambitions to launch a crewed vehicle into space. Internally, however, he quickly became known as a charismatic but controlling and conflict-prone leader, and he broke with the organisation in 2014, going on to establish Rocket Madsen Space Lab.

To the outside world Madsen appeared eccentric and media-hungry. Behind that facade, the subsequent investigation and trial painted a picture of a man with extreme sexual fantasies, deep isolation and a controlling personality structure.

The crimes

On 10 August 2017, 30-year-old Swedish journalist Kim Wall boarded UC3 Nautilus at Refshaleøen harbour in Copenhagen. She was there to interview Madsen for a feature on his life as an inventor. It would be her final assignment.

The following morning, on 11 August, Nautilus was spotted in Køge Bugt, where it sank shortly afterwards. Madsen was rescued and brought ashore, and initially claimed he had dropped Wall off at Refshaleøen the previous night. When her dismembered torso washed ashore at Amager ten days later, Madsen changed his account: Wall had died in an accident on board, he now claimed, after a heavy hatch struck her on the head.

Forensic examination disproved that explanation. Wall had stab wounds to her genitals inflicted at or around the time of death, and her body had been systematically dismembered using saws and knives, with her head and limbs weighed down with metal pipes and submerged in the bay. Police also found videos on Madsen's computer depicting the killing and dismemberment of women.

The victim

[Kim Wall](/tags/kim-wall) was 30 years old, born in Trelleborg, Sweden, and educated at, among other institutions, Columbia Journalism School and the London School of Economics. She had reported from North Korea, Cuba, Haiti and Uganda for outlets including The Guardian, The New York Times and Harper's Magazine, and was widely respected for her ability to find the human story in society's margins.

Wall was living in Copenhagen with her partner and was in the process of packing up ahead of a move to Beijing when she accepted the opportunity to interview Madsen. Her death prompted an outpouring of grief across the international journalism community, and her family subsequently established the Kim Wall Memorial Fund for female reporters.

Investigation and trial

Copenhagen Police conducted an extensive investigation led by detective superintendent Jens Møller Jensen. Divers and sonar scans located Wall's severed body parts in Køge Bugt in October 2017. The physical evidence — including DNA, material found on Madsen's computer and the submarine itself — proved decisive.

The trial opened at Copenhagen City Court on 8 March 2018. Madsen denied murder but admitted to dismembering the body. On 25 April 2018 he was found guilty of premeditated murder, dismemberment and sexual assault of a particularly dangerous nature, and was sentenced to life in prison. The Eastern High Court upheld the verdict on 26 September 2018.

In October 2020, Madsen briefly escaped from Herstedvester Prison carrying a replica pistol and a fake bomb strapped to his body. He was apprehended within a few hundred metres of the prison gates.

Legacy

The case became one of the most widely covered criminal cases in modern Danish history. HBO produced the documentary series *Undercurrent: The Disappearance of Kim Wall* (2020), followed by the Discovery+ series *Løgnen om ubåden* (2022), in which Madsen effectively confessed to the murder during a prison interview. The case has been examined in books including Thomas Djursing's *Raketmanden* and in numerous podcasts, among them episodes of [Mørkeland](/tags/morkeland) and various international true crime formats.

The case sparked a broader debate about the safety of female journalists and about how media organisations handle charismatic sources. Peter Madsen continues to serve his life sentence.