The investigation that surrounds the 1986 murder of Swedish Prime Minister Olof Palme is as dense and intricate as that surrounding the conspiracy-laden assassination of late American President John F. Kennedy.

Swedish authorities are still officially in the dark when it comes to who pulled the trigger on a Stockholm street on February 28, 1986.

Palme was gunned down after having left the Grand Cinema. One bullet pierced his spine and vital organs, the other grazed his wife, Lisbet, who was with the Prime Minister. Hours later, Palme was dead, setting authorities on a manhunt that remains unresolved until today.

Three years after the shooting, Christer Pettersson, a petty Stockholm criminal, was sentenced to life in prison for the murder. Later on that year, however, Pettersson was acquitted and released after it came to light that authorities had influenced Lisbet Palme's identification of the man from a police lineup.

130 confessions and counting

In 1998, the Swedish Supreme Court rejected an appeal to reopen the case against Pettersson, reopening the search for the killer in what has become one of Sweden's largest murder investigations.

Numerous conspiracy theories have been put forward - ranging from plots by secret services in several countries, Kurdish separatists and domestic extremists.

Detective Superintendent Stig Edqvist has led the investigation since 1997. He says around 130 people have confessed during the over two-decade-long investigation. Each of those accounts, however, was deemed false.

Last year, the Swedish parliament decided to abolish the 25-year statute of limitations for serious offenses such as murder, allowing the Palme investigation to continue indefinitely.

"It would have been terrible if a decisive puzzle piece had come in and could not be used," said prosecutor Kerstin Skarp, who has also been involved in the investigation since 1997.

Anniversary to bring surge of 'new leads'

Palme was prominent internationally as a vocal critic of the military junta in Chile and the apartheid system in white minority-ruled South Africa at the time. He had also served as mediator between Iran and Iraq.

At home, he was regarded as a controversial politician by some and was on "at least 20 death lists," detective Edqvist said.

Investigators have found it difficult to explore leads pointing to major intelligence authorities, for instance the CIA in the US and the KGB of the former Soviet Union.

Edqvist says he and his team expect a flood of information from the public on and around the anniversary of the murder. At national police headquarters, a vault containing the so-called Palme archives houses at least 3,600 binders.

Despite the mounting information, most of which has proved misleading, and the disconcerting fact that there are "very few really hot leads right now," detective Kerstin Skarp is reluctant to give up hope.

"I wish I could say that it will be solved, but I will never say that it won't," Skarp said.

Author: Gabriel Borrud (AFP, dpa)
Editor: Toma Tasovac