The decision leaves Sture Bergwall — for many years known as Thomas Quick and long considered Scandinavia’s worst serial killer — with just one murder on his record.
The prosecution said on Monday it would not prosecute Bergwall, 63, for the deaths of a Dutch couple, Marinus och Janni Stegehuis, who were found stabbed to death at a highway rest stop in Appojaure, in northern Sweden, in 1984.
He was convicted of their murders in January 1996 after confessing to the crime. But he later retracted his testimony, and a retrial was ordered.
The prosecution authority said in a statement it was dropping charges in a retrial “since there is not sufficient evidence that Sture Bergwall committed the crime.”
The Bergwall case has sparked a controversy in Sweden, because of the ease with which he was found guilty of the eight murders, which occurred between 1976 and 1988.
Swedish Justice Minister Beatrice Ask vowed last year to conduct a review of how the courts could have convicted him.
During therapy for an armed robbery conviction, Bergwall confessed to all eight murders along with more than 20 others committed in Sweden, Norway and Finland — for which he was not tried — often describing how he butchered his victims and in at least one case ate the body parts.
In December 2008, however, he suddenly withdrew all his confessions, saying he had been craving attention at the time and had been heavily medicated by doctors.
He has since been acquitted in three cases, had the charges dropped in four cases, and has been granted a retrial in the remaining case.
Bergwall is serving a life term in a psychiatric institution.