The victim, who was released from prison last month, was admitted to hospital after being beaten with a golf club. He received several blows to the head, but was able to leave hospital on Sunday.
The suspected attackers, all in their 20s, were arrested on Wednesday after convicted rapist Niklas Lindgren, who is also known as Hagamannen, was attacked outside his home at a dormitory in Övertorneå in northern Sweden on Saturday.
The men, who all deny the alleged attack, were remanded in custody on Friday afternoon.
According to Swedish tabloid Expressen, the suspects are well-known to police and have previously been convicted of a number of crimes, including assault, car theft, drunk driving, as well as the possession of arms and drugs.
Lindgren was imprisoned in 2006 for raping several women in the northern city of Umeå between 1999 and 2005. In two of the cases he also tried to kill his victims.
A long and complex police investigation led to the arrest of the then 33-year-old father-of-two in March 2006 as police were able to link his DNA to a number of the rapes.
He was released on parole in July after having served two-thirds of his 14 year prison sentence.
Many in Umeå expressed fear and concern after Lindgren walked out a free man from the Skogome prison in Gothenburg.
As he was set free, a demonstration against sexual violence toward women was held in Umeå where he has been granted permission to return despite the public outcry.
The Swedish Prison and Probation Service – which supervises criminals – had initially decided not to allow Lindgren to return to Umeå. The committee had argued that the risk was too high he would reoffend, but also that he himself could be a target for retribution. That decision was reversed by an appeals court.
“Of course, we know that there is a threat against him and that can mean that we need to protect him, but we aren’t that far along yet,” police spokesman Börje Öhman said at the time.
Former prosecutor Sven-Erik Alhem said he was appalled by the news that Lindgren might have been attacked.
“The private administration of justice is intolerable,” he said.
Lindgren remains obligated to attend weekly meetings as part of an official rehabilitation program for sex criminals as well as stay in close contact with his probationary officer.