Nearly two weeks later, the 30-year-old’s headless torso was found on a beach in Denmark’s capital city, Copenhagen. The rest of her body still hasn’t been found and Madsen, 46, is in custody and charged with manslaughter.
There is still a lot of mystery surrounding her death, as Madsen maintains he is innocent. Here is a timeline of the events.
Wall is last seen alive as she departs on a submarine trip with Madsen in Copenhagen Harbour.
Wall’s boyfriend alerts authorities that the 40-tonne, nearly 18-metre-long sub, named the UC3 Nautilus, hadn’t returned from a test run. The Danish navy launches a rescue operation, including a search by two of its helicopters and three of its ships.
Madsen is found alive and is picked up by a private boat. The submarine sinks when he is rescued.
Madsen appears on Danish television after he’s rescued to discuss the submarine’s sinking, according to The Guardian. Footage aired on Denmark’s TV2 channel shows him getting off the private boat and making a thumbs-up sign as he walks away. “I am fine, but sad because Nautilus went down,” he tells Danish media, TV2.
Madsen also says “a minor problem with a ballast tank … turned into a major issue” ultimately caused the sinking of the vessel.
When police question him, Madsen says he dropped Wall off on a Copenhagen island before the submarine sank. He then changes his story and tells authorities “an accident occurred on board that led to her death” and he buried her at sea at an unspecified location.
Hours later, police charge Madsen with manslaughter. Authorities say they believe he intentionally sank the submarine.
The submarine is found at a depth of seven metres south of Copenhagen. Divers are initially unable to safely enter it.
WATCH: Madsen is arrested for murder after being rescued from sea
Police secure Wall’s hair brush and toothbrush, and the DNA from the items matches blood they find on the submarine.
The same day, a judge orders that Madsen be held in pre-trial detention for 24 days while the investigation into Wall’s disappearance continues.
Danish police are able to search the submarine but do not find a body.
The torso of a woman is found on a beach by a member of the public who was cycling on Copenhagen’s southern Amager island, near where Wall was believed to have died.
Copenhagen police say the woman’s head, arms and legs had “deliberately been cut off” from her body.
DNA tests confirm it’s Wall’s torso. Police investigator Jens Moeller Jensen says Wall’s torso was attached to a piece of metal “likely with the purpose to make it sink.”
The body “washed ashore after having been at sea for a while,” he says. He adds that police found marks on the torso indicating someone tried to press air out of the body so that it wouldn’t float.
The cause of the journalist’s death is not yet known, police say, adding they are still looking for the rest of her body.
WATCH: Danish police confirm headless torso is missing journalist Kim Wall
Who is Wall?
Wall, a Sweden-born freelance journalist, studied at the Sorbonne University in Paris, the London School of Economics and at Columbia University in New York, where she graduated with a master’s degree in journalism in 2013.
According to her website, she writes about identity, gender, pop culture, social justice and foreign policy.
She lived in New York and Beijing, her family said, and had written for The New York Times, The Guardian, the South China Morning Post and Vice Magazine, among other publications.
Her family told The Associated Press she was working on a piece on Madsen. They added she had worked in many dangerous places as a journalist, and it was unimaginable “something could happen … just a few miles from the childhood home.”
In an email to The Associated Press, the family said it received the confirmation of her death “with boundless sadness and dismay,” adding “the tragedy has hit not only us and other families, but friends and colleagues all over the world.”
Who is Madsen?
Madsen built the world’s largest homemade submarine in 2008 after crowdfunding the cost. The UC3 Nautilus was his third submarine project.
A self-taught aerospace engineer, Madsen was one of several entrepreneurs who founded an association known as Copenhagen Suborbitals to develop and construct a manned spacecraft and submarines.
The group split in 2014, and Nautilus, described as the world’s largest privately built submarine, is currently owned by Madsen’s company Rocket Madsen Space Lab.
— With files from the Associated Press