Danish inventor Peter Madsen has been formally charged with the murder of the Swedish journalist Kim Wall, according to a public prosecutor.

In what was definitely one of the strangest news stories of last year, Madsen – who had designed and piloted his own custom submarine – was accused of deliberately killing Wall after she disappeared. Wall was last seen boarding Madsen’s self-built submarine for an interview. Her headless, dismembered torso was found floating off the coast of Copenhagen ten days after her disappearance.

According to prosecutor Jakob Buch-Jepsen, Madsen has been charged with murder and indecent handling of a corpse. He is also charged sexual assault, without intercourse, of “a particularly dangerous nature”.

Madsen repeatedly changed his story in interviews with police. He initially denied dismembering Wall’s body, but said the 30-year-old journalist died when a heavy submarine hatch accidentally fell on her head. Later, he changed his story, saying that she died of carbon monoxide poisoning, and that he had indeed dismembered her, weighed the body parts down, and released them into the sea.

Buch-Jepsen dismisses both of these accounts. He says that Madsen either strangled Wall or cut her throat at some point after she boarded his submarine. Prosecutors allege that Wall’s body was found with 15 stab wounds, including 11 around the genital area.

During the police investigation, an examination of Madsen’s computer found material of women being tortured and killed.

If found guilty, Madsen faces possible life in prison. The start of the trial has been set for the 8th of March and a verdict is expected on the 25th of April.