Swedish prosecutors will announce on Wednesday whether they plan to press charges or close the investigation into the unsolved 1986 murder of prime minister Olof Palme.
Palme was killed on February 28, 1986, after leaving a Stockholm cinema with his wife Lisbet to walk home, having dismissed his bodyguards for the evening.
An unidentified attacker shot Palme in the back and fled, leaving the 59-year-old dying in a pool of blood on the sidewalk.
More than 10,000 people have been questioned but authorities do not currently have anyone placed under formal suspicion.
"Chief prosecutor Krister Petersson will announce his decision and speak about the investigation together with the head of the investigation Hans Melander," the prosecution authority said in a statement on Friday.
Over the years, more than 130 people have claimed responsibility for the murder and the case files take up 250 metres of shelf space.
Christer Pettersson, a petty criminal and drug addict, was convicted of the crime in July 1989 after Palme's widow identified him in a widely-criticised line-up.
But he was freed months later by an appeals court which dismissed her testimony on a technicality. Pettersson died in 2004 while Palme's widow passed away in 2018.
Over the years, investigators have suspected Turkey's Kurdish rebel group the Kurdistan Workers' Party (PKK), the Swedish military and police, and the South African secret service among others.
Petersson took over the investigation in 2017.
Experts and Swedish media have in recent months suggested that the most likely scenario would be that the case will be closed, because the main suspects speculated about in the media in recent years are all dead.
Palme, a Social Democrat known as a great orator, was a controversial figure who infuriated Washington with his vocal opposition to the US war in Vietnam. He also backed communist governments in Cuba and Nicaragua, and spoke out against apartheid and nuclear power.
His murder sent Sweden, normally a tranquil and safe country, into shock.
Palme was a controversial figure who infuriated Washington with his vocal opposition to the US war in Vietnam