The man was charged with murder and disturbing the peace of the dead, as well as with child rape in connection with a separate incident from 2007.
The 37-year-old has admitted to causing the death of the Swedish teenager, referred to in the media as Johanna, but denies the murder charge. During his detention, the man was also served on suspicion of child rape.
"He has said himself that he killed Johanna by mistake during a sexual activity that went too far," police spokesperson Robert Loeffel told the Aftonbladet newspaper.
Deputy chief prosecutor Yvonne Rudinsson said that material found on the man's and girl's computers and cell phones proves that the two had a brief love affair that began around Midsummer in 2010.
The contents of the man's computer also provided evidence that he had had contact with a large number of women and that in several cases, he had pretended to represent a fashion company and wanted to take pictures.
The relative of the 37-year-old alerted authorities about the killing at around the time they heard from the Johanna's mother, who couldn't reach her daughter after she had gone to meet the man she thought was a representative of a fashion company.
She contacted police after receiving a call from the suspect, who he claimed he had killed a girl, according to Aftonbladet.
Johanna was found dead in a wooded area outside Lindshammar in southeastern Sweden after a major police operation.
Investigators concluded she was strangled to death in the 37-year-old's apartment and that her body was then dumped in the woods.
The man maintained that Johanna's death was accidental and occurred in connection with a sex act that went too far.
Loeffel explained that the man had also been charged with disturbing the peace of the dead because he drove Johanna's dead body to the woods before disposing of it.
The suspicion of child rape involves a girl who was a minor when the man is alleged to have had intercourse with her in Svenljunga in 2007. The information emerged during the the publicity following the murder of Johanna.
The 37-year-old has undergone a so-called Section 7 examination, or a "short examination conducted by a forensic psychiatrist."
The psychiatrist indicated that there was no reason to suspect that the man suffers from a serious mental disorder.