Updated

One of the most talked-about and macabre court cases in recent Danish history is set to conclude Wednesday when the verdict is handed down on whether Peter Madsen tortured and murdered a Swedish journalist during a private submarine trip.

The 12-day trial has seen a series of gruesome allegations made against the inventor, but the autopsy of the cut-up remains of Kim Wall has not been able to specifically identify a precise cause of death.

Wall, 30, who wrote for The New York Times, The Guardian and other publications, set out on the submarine on a sunny August evening last year to interview Madsen, the co-founder of a company that develops and builds manned spacecraft. Her remains were found in plastic bags on the Baltic Sea bed weeks later.

After offering various explanations, the 47-year-old Madsen has claimed that Wall died as a result of a buildup in pressure inside his home-made UC3 Nautilus submarine. On Wednesday at 1 p.m. local time (1100 GMT), a judge and two jurors will rule whether her death was an accident or a murder.

Prosecutors are seeking a life sentence for Madsen, who has confessed to cutting up Wall's body up into pieces after he was unable to lift her corpse through the submarine tower so he could bury her at sea.

"What do you do when you have a large problem? You make it smaller," he told the Copenhagen City Court. "I am really, really sorry about what happened."

During the trial that began on March 8 and lasted for 12 court days, prosecutor Jakob Buch-Jepsen sought to prove there was no accident and that Wall may have been tied with her own stockings before Madsen impaled her.

He also said Wall's dismembered torso had multiple stabs, including in the genitals and that semen had been found in Madsen's underwear. Buch-Jepsen also said videos of women being tortured and killed were found on his personal computer — snuff-like videos that he did not make himself. And Madsen had, according to the prosecution, brought along tools he normally didn't take when sailing.

While arguing that Madsen is not insane, Buch-Jepsen quoted a court-ordered psychiatric report that described him as "emotionally impaired with severe lack of empathy, anger and guilt" and having "psychopathic tendencies."

Before the trial, Madsen had offered shifting explanations for Wall's death — something Buch-Jepsen used against him. The pair clashed verbally as Madsen brushed off Buch-Jepsen allegations.

Madsen initially said he had dropped Wall off on a Copenhagen island several hours into their submarine trip. Then he said Wall died accidentally inside the submarine when a hatch fell and hit her on the head — but no indication of a skull injury was found when her head was finally located.

He finally said Wall died because of a pressure problem inside the submarine which Madsen is suspected of having sunk deliberately. Wall, he said, had had "a wonderful evening until it ended in an accident."

Buch-Jepsen said forensic experts had "found nothing" to back Madsen's claim and that there is a risk he could commit "the same kind of crime again."

In Denmark, life sentences are on average 16 years, but the term can be extended if necessary. Or he could be sent to a secure mental facility and locked up as long as he is considered a danger to others.

Madsen's lawyer Betina Hald Engmark has described it "a horror story" but that the prosecution case was based "on undocumented claims." Clearly, she says Madsen did something "horrible" by cutting Wall into pieces, and that he should only be sentenced for that. Under Danish law, indecent handling of a corpse can lead to six months in jail.

"It is not my client's duty to prove that he is innocent. It is the task of the prosecutor to prove that he is guilty," she said in her final argument before the court room.

The parents of the Swedish reporter — Ingrid and Joachim Wall — have listened silently during the trial.

As they have done for most of the time since losing their daughter who had reported from post-earthquake Haiti, among other places, studied at Paris' Sorbonne University, the London School of Economics and Columbia University in New York.