Authorities indicated the death was an apparent homicide but gave no details.
"The report is unambiguous. We have a clear answer as to what the cause of death was, but we are not yet ready to make this public," said Yngve Skovly, a lawyer with the police in Sunnmore.
Aarseth had sustained injuries and appeared to die after a violent struggle, The Local.No reported.
A sniffer dog found the body on a steep slope covered in dense vegetation Saturday in Alesund.
The Norwegian Criminal Investigation Service sent DNA samples from the body for forensic analysis.
Police said they wanted to take DNA from men who were near the site where the body was found, The Local.No said.
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