The Danish inventor at the center of the mysterious death of Swedish freelance journalist Kim Wall, whose dismembered body was found off the coast of Copenhagen in August, was formally charged with killing her Tuesday.

Prosecutors say that during a trip on his private submarine, Peter Madsen, 47, either strangled or cut Wall's throat before severing her body and tossing it into the sea. Madsen is charged with homicide, dismemberment and the indecent handling of a corpse.

"This is a very unusual and extremely brutal case which has had tragic consequences for Kim Wall and her relatives," prosecutor Jakob Buch-Jepsen said in a statement from the Danish prosecution authority.

Wall's disappearance and gruesome death has drawn international attention, demonstrating the risks female freelance journalists can face. Friends and family say Wall, 30, was a brave reporter who during her brief career reported from Sri Lanka, the Marshall Islands and North Korea.

Madsen in October denied killing Wall, and said she died of carbon monoxide poisoning inside his submarine while he was on deck. Wall boarded the submarine on Aug. 10 to report a story about Madsen, according to her family. Madsen is known in Denmark for raising money through crowdfunding to build rockets and submarines.

She was reported missing the next day. Madsen was rescued from Koge Bay that day after, according to police, purposely sinking his vessel, a 60-foot UC3 Nautilus.

Prosecutors are seeking a sentence of life in prison for Madsen or, based on the results of a psychiatric evaluation, that he be sent to a mental institution. Prosecutors said the killing was premeditated but did not provide a motive.

"The interest in the case has been enormous," Buch-Jepsen said. "However, we hope the media will respect that further evidence in the case must be presented in court and not in the press."

Madsen was taken into custody Aug. 12, and has since repeatedly altered his account of the circumstances that led to Wall's death. Before claiming in October that she died of carbon monoxide poisoning, Madsen in August said he dropped Wall off shore in Copenhagen before his submarine sank. He then told a Danish court in September that while giving Wall a tour of his boat, he lost his grip on a 150-pound hatch, which collided with Wall's skull. He told prosecutors at the time he panicked and gave Wall a "burial at sea."

"In the shock I was in, it was the right thing to do," Madsen told the court, according to Agence France-Presse.

In early October, divers found Wall's dismembered remains. Wall's legs were found in plastic bags weighed with metal, according to the Associated Press, and her recovered head showed no signs of fracture - which suggested she had not been struck by a hatch. Another bag contained a knife and Wall's clothing. Weeks earlier, a naked torso that had been stabbed 15 times was recovered nearby.

Madsen, who had previously been charged with manslaughter, was being held in Vestre Prison in Copenhagen.

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