The woman, believed to be in her late-fifties was locked away in a 15 sqaure metre cabin located near Eksjö, close to the town of Jönköping.
“We suspect a man of having held a woman captive against her will for several years and to have mistreated her during that time,” Jönköping police spokesperson Johan Frisk told AFP.
Neither the man nor the woman have been identified, but it is believed they had been a couple for some time.
According to Sveriges Television, the man was declared dead in Sweden’s national registry eight years and residents in the area knew him under a completely different identity.
At a remand hearing on Friday afternoon, the 58-year-old man denied any wrong doing through his lawyer Uno Karlsson.
However, the man was nonetheless ordered to remain in custody pending the filing for formal charges.
Police remain tight lipped about the case but a request for a public defender includes information that the woman may have been locked up for as long as nine years, according to the Smålands-Tidningen newspaper.
The newspaper reported that authorities had at first been investigating whether the man had been abusing the woman.
After questioning witnesses last week, police then brought the man in for an interrogation on Wednesday.
Information gathered during the interview lead police to arrest the man and expand their investigation in also included looking into the illegal detainment of the woman.
Police refuse to comment on the woman’s condition, other than saying she is doing fine under the circumstances.
According to the newspaper, the woman is in a hospital, is seriously ill, and weighs only 35 to 40 kilograms.
There are few details on how and why the woman was locked up, other than that she was confined to a 15 square metre cabin.
Despite suspicions that the woman has been held for years, Smålands-Tidningen also uncovered evidence that the woman has been allowed out in public.
The newspaper also spoke with a source who reported having met the pair and is surprised over revelations that the woman may have been the victim of abuse.
According to prosecutor Klas Hellgren, both crimes of which the man is suspected have been committed continuously since 1999 through August of this year.
The Aftonbladet daily meanwhile reported on its website that the couple had long lived on the fringe of society and had moved to the small cabin on a camping ground in 1999.