In explaining his decision in a press release, the prosecutor said that new information about the murder had emerged in media.
I have decided to resume the preliminary investigation after, in connection with the review of the case by SVT and Dagens Nyheter, I have found data that I consider to be new circumstances that warrant the resumption of the preliminary investigation," says chief prosecutor Niclas Wargren.
But the prosecutor said that other information has come to light that is of primary importance.
"However, it is primarily other information that underlies my decision to resume the preliminary investigation. What it is, I will not comment further at this time," said chief prosecutor Niclas Wargren in a press release.
The boys' lawyer, Thomas Olsson told news agency TT that he did not know exactly what the prosecutor had in mind, but had a good idea.
Olsson says that he is convinced that the murder confession by the two boys does not exist as evidence, so he is "not surprised" by the decision to resume the investigation.
"There are severe doubts about this confession and if it exists," Olsson told Radio Sweden.
Dagens Nyheter has reported about how the boys were questioned on at least 31 different occasions, and there has been speculations that the boys felt pressured into a confession. The role of a psychology professor played in the investigation, where he gave instructions to the police, has also been questioned.