The Swedish Board of Forensic Medicine has submitted its statement to the district court.
"The grounds are confidential," prosecutor Markus Hankkio tells the newspaper.
The statement means the male suspect, who identifies as a woman, could be sentenced to prison if convicted.
The Swedish Board of Forensic Medicine's assessment may change.
On the night before Boxing Day, a 25-year-old woman disappeared after a night out. The next day she was found murdered. A 26-year-old man was arrested in connection with the discovery; he has admitted to aggravated assault but denies murder. He has previously been convicted of aggravated child pornography and attempted kidnapping.
