The trial of an inventor accused of torturing and killing a Swedish journalist on his private submarine is now underway in Copenhagen, Denmark.Peter Madsen, a Danish inventor charged with murder and indecent handling of a corpse, has denied killing Kim Wall. He is accused of torturing 30-year-old Wall before either cutting her throat or strangling her.Wall, a freelance journalist who wrote for The New York Times, The Guardian and other publications, embarked on Madsen's submarine on Aug. 10 to interview the 47-year-old 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, and her torso was found stabbed multiple times.Prosecutor Jakob Buch-Jepsen said in court that after Wall boarded the submarine, she texted and sent pictures to her Danish boyfriend. The last messages were sent after 8 p.m. local time and included:"I'm still alive btw.""But I'm going down now!""I love you!!!!!""He brought coffee and cookies though."Later that evening, Wall's boyfriend was unable to reach her, looked for her and then reported her missing, the prosecutor said.Madsen, 47, is also charged with "sexual relations other than intercourse of a particularly dangerous nature" after her remains were discovered to have stab wounds in and around her genitals. He appeared irritated as he denied any suggestion of sexual activity with Wall.Buch-Jepsen read from a psychiatric report describing Madsen as an intelligent man "with psychopathic tendencies." Madsen himself told the court Thursday that he was "a promiscuous person."Pictures of Wall's body are so graphic, most of them will only be shown to those judging the case, the prosecutor said. Only a picture of her wrist was shown in court to show marks, which the prosecutor said matched straps that were found in the submarine.Investigators never found Madsen's phone, but they were able to recreate its contents, the prosecutor said. Hours before boarding the submarine with Wall, Madsen had searched for the words "beheading," "girl" and "agony."A video of a woman having her throat slit had been played on his phone. Videos showing women being tortured and executed also were found on his computer.Madsen had offered shifting explanations for Wall's death prior to the trial. He initially told authorities he had dropped Wall off on a Copenhagen island several hours into their submarine trip. Then he said that Wall died accidentally inside the submarine when a hatch fell and hit her on the head. On Thursday, he described how he found Wall lifeless after a sudden pressure problem in the submarine."I could not open the hatches. I heard Kim, it was not good," he said. He added that he tried to give her first aid when he finally reached her, but stopped because it was impossible to stay inside. "There was a risk of having a submarine with two deaths," he told the court.Madsen says he dismembered Wall's body so that he could bury her at sea because he couldn't lift her up the submarine tower.The prosecution claims Wall's murder was premeditated because Madsen brought along tools he normally didn't take when sailing.A verdict is expected April 25. If found guilty, Madsen faces between five years and life in prison - which in this case means 16 years that could be extended as long as Madsen is deemed dangerous - or he could be locked up in a secure mental facility if deemed necessary by psychiatrists, for as long as he's considered sick and a danger to others.