Danish inventor Peter Madsen is due to go on trial over the death of Swedish journalist Kim Wall aboard his homemade submarine last August.
He faces charges including murder, dismemberment and “sexual relations other than intercourse of a particularly dangerous nature”.
He denies murdering her after she boarded the vessel in pursuit of a story, but admits cutting up her body.
Around 40 witnesses are set to give evidence over the next few weeks.
Prosecutors will attempt to fill in the gaps in an already horrific jigsaw puzzle of details surrounding the 30-year-old’s death, says the BBC’s Maddy Savage in Copenhagen.
A cyclist found the remains of the journalist’s dismembered torso on a nearby beach 10 days after she disappeared following an interview with Peter Madsen on his submarine.
Weeks later, police divers discovered other parts of her body in plastic bags weighed down with metal.
Mr Madsen told police she had died when a heavy hatch on the submarine fell on her head.
However, he later changed this account and maintained she had been killed by carbon monoxide poisoning inside the submarine while he was up on deck.
If he is found guilty Peter Madsen, 47, is likely to get a life sentence – typically meaning around 15 to 17 years in prison without parole – or be sent to a secure psychiatric hospital.
Ms Wall had had a long career in journalism, having previously reported from North Korea, the South Pacific, Uganda and Haiti, writing for the New York Times, Guardian, Vice and the South China Morning Post.