Divers are hunting for Wall's body around Køge Bay and Öresund, and sonar detection devices are being deployed in the search.
Peter Madsen, aged 46, had originally claimed 30-year-old Swedish writer Kim Wall disembarked safely on a Copenhagen island but has since admitted she was killed in an "on board mishap".
The sunken submarine was located by the emergency services on August 11, according to local media, but Wall's body remained unfound.
Ms Wall was last seen on Mr Madsen's submarine on the night of 10 August. The submarine was later reported missing, and rescue crews located it at around midday on 11 August in Køge Bay, about 30 miles south of the Danish capital.
Police then later claimed that Madsen had given them a "different explanation".
Littleton cops shoot, kill bull on the loose
A bull that escaped from a livestock auction and was on the run for several days in MA has died. For the next few days it was seen wandering around Littleton, Groton and Ayer.
Wall, a 30-year-old freelancer based in NY and China, was known among her friends as an intrepid reporter, skilled at exploring hard-hitting topics in obscure, and at times risky, locations.
TV2 showed images of Madsen being questioned by police after his rescue.
Madsen has been charged with negligent manslaughter and police believe he deliberately sank the submarine.
"I don't check the background when a journalist calls and asks 'Can I interview you?'" Madsen said indifferently as he entered a police auto.
In addition to The South China Morning Post, her work has appeared in Harpers, The Guardian, the New York Times, Foreign Policy, the Atlantic, and many other publications. She received a bachelor's degree from the London School of Economics & Political Science.