'The Investigation' on HBO: What to Remember About the 2017 Submarine Case

The Investigation

The 2017 murder of journalist Kim Wall is at the center of HBO's latest, true-crime drama starring 'Game of Thrones' actor Pilou Asbæk.

While HBO has no shortage of addictive true-crime docuseries, the premium cable network has also produced a number of chilling and fascinating dramatized versions of real-life events. And The Investigation is the latest scripted series to capture audiences by recounting the exhaustive effort the Danish police put into solving “the submarine case” and the events surrounding the 2017 murder of Swedish freelance journalist Kim Wall, who died and was dismembered aboard a miniature submarine while interviewing its owner, Danish entrepreneur Peter Madsen. 

Unlike typical true-crime dramas, which tend to recount gritty details of the crime at hand, Mindhunter director Tobias Lindholm keeps the series focused entirely on the investigation, with Søren Malling (A Hijacking) leading the cast as Jens Møller, Head of Homicide for the Copenhagen Police, alongside Pilou Asbæk (Game of ThronesEuron Greyjoy) as chief prosecutor Jakob Buch-Jepsen. Pernilla August (Star Wars prequels) and Rolf Lassgård (The Hunters) portray Wall’s parents, Ingrid and Joachim.

That said, ET has put together a guide to the submarine case and the key characters pivotal to The Investigation

The Key People

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Swedish freelance journalist Kim Wall was 30 years old when she secured a last-minute interview with entrepreneur Peter Madsen just days before she and her boyfriend were to move to Beijing. Madsen, who was 46 years old at the time, was an engineer that worked on rocket engines for space travel and built his own fleet of miniature submarines. On Aug. 10, 2017, he invited Wall to join him on one of his creations, UC3 Nautilus, a two-hour, in-person tour and interview. It was later reported that Madsen, who was married at the time, was a regular at fetish parties and had invited other women onto his submarine. 

The resulting investigation was led by Jens Møller, Head of Homicide for the Copenhagen Police, while Jakob Buch-Jepsen handled the prosecution against Madsen. 

Timeline of Events

After the submarine failed to return to the harbor, Wall’s boyfriend reported her missing to the police. The next day, Aug. 11, the Nautilus was spotted before it eventually sank to the bottom of the Køge Bay and Madsen was rescued by police. 

No sooner than Madsen was rescued, he was charged with negligent manslaughter as the police launched an investigation into the whereabouts of Wall and why the submarine sank. While in custody, Madsen’s account of events changed several times, from first asserting that he dropped Wall off on land to her dying onboard after an accident and that she was buried at sea. During a court hearing on Sept. 5, he said she was fatally hit on the head after he lost grip of the hatch.  

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On Aug. 21, Wall’s torso washed ashore and showed signs of knife wounds that were made “around or shortly after her death.” By October, after an exhaustive search by divers, Wall’s remaining body parts, her clothes as well as a saw were found at the bottom of the bay. A forensics review of her body showed no signs of trauma to the head. On Oct. 30, Madsen reportedly changed his story about Wall’s death and admitted dismembering her body. 

By January 2018, Madsen was charged with murder, indecent handling of a corpse and sexual assault. He was eventually found guilty of all charges and sentenced to life in prison. Two years later, Madsen briefly escaped from prison before being quickly apprehended again.

In 2020, Madsen reportedly confessed to murdering Wall in secretly recorded phone calls for a docuseries called The Secret Recordings With Peter Madsen. According to several publications, he was allegedly recorded saying, “There is only one who is guilty, and that is me.”

Why Kim and Peter Don’t Appear in ‘The Investigation’ 


One of the things that sets the series apart is the fact that Wall, Madsen nor the events that may have taken place aboard the submarine are never depicted onscreen. In an interview with HBO, Lindholm said he wanted to start the story with news about the missing submarine.

“And that led me on to trying to analyze what the [true-crime] genre dictates,” he said. “And I realized that true crime in its nature is, of course, obsessed with the crime... So, I thought to myself, ‘What if we invented a new genre called true investigation?' Where we don’t really talk so much about the crime, but we talk about the investigation and we go into what that is.”

Admittedly, “It is kind of dry,” Lindholm continued. (While fascinating, at times, audiences’ patience may be tested by not being able to see what may have happened.) “But I wanted to be honest, this is not about the submarine case, this is about the investigation.”


The Investigation airs Mondays at 10 p.m. ET/PT on HBO and is available to stream on HBO Max.