Mikael Andersson, from Lidköping in western Sweden, disappeared from a party in Axvall outside of Skara last weekend.
His family reported him missing on Tuesday. Following an inspection of his battered car police began a murder investigation on Thursday.
Västra Götaland police announced in a press release on Friday that they are certain that Mikael Andersson has been murdered and that they had arrested four people in connection with the investigation.
“We have strong indications that he has been murdered,” confirmed police spokesperson Thomas Fuxborg.
One man is in custody on suspicion of murder and two further men suspected of complicity to murder. A woman has been arrested on suspicion of harbouring a criminal.
A further, fifth person, was arrested on Saturday. He is being detained on suspicion of complicity to murder.
All five deny the charges.
Police are continuing the search for the body of Mikael Andersson over the weekend. Police have confirmed that they have identified the murder scene but have not released any further details of the crime or the roles played by the five suspects.