Olof Palme was killed by a conspiracy the official investigation never solved

The street, and the shot

Late on the evening of 28 February 1986, Sweden's prime minister, Olof Palme, was walking home through central Stockholm with his wife, Lisbeth. They had been to the cinema, an ordinary night out, and, characteristically for Palme, they had no bodyguards; the couple had dismissed their security detail earlier that day. As they walked along Sveavägen just after 23:20, a man stepped up behind them and fired. One shot struck Palme in the back and killed him. A second grazed Lisbeth. The gunman ran, disappeared up a set of steps toward a side street, and was gone.

What followed became the largest and most criticised criminal investigation in Swedish history. The crime scene was not properly sealed for hours. Rivalries broke out between national and regional police. Leads multiplied and contradicted one another. Forty years later, after thousands of tips, several suspects, one overturned conviction, and two opposed official conclusions, no one has been convicted of the murder, and the case is formally closed as unsolved.

The vacuum has never been neutral. A head of government shot dead in a public street, in one of the safest capitals in the world, is exactly the kind of event that a single random cause seems too small to explain. Into that gap poured decades of theories, some reckless, some serious, none ever proven.

The suspects who came and went

The first great error came early. The regional police chief who took charge, Hans Holmer, built the investigation around the theory that the Kurdish militant group the PKK had killed Palme. Months of effort went into it. Nothing came of it: no weapon, no charge, no corroboration, and the PKK denied any part. The fixation is now widely regarded as having squandered the crucial early window when the trail was still warm.

Then came a man the case could actually put in a courtroom. Christer Pettersson, a local figure with a record of violence and addiction, was arrested, picked out by Lisbeth Palme in a line-up, and convicted of the murder in 1989. Within months an appeals court threw the conviction out, finding the identification unreliable and the evidence too thin to stand. He is the only person ever convicted of the crime, and the conviction did not survive the year.

Around and after that ran the bigger, darker theories, each anchored to a real feature of Palme's political life. He was a fierce and prominent opponent of apartheid, and in 1996 a former South African officer alleged that Pretoria's security services had ordered him killed, naming the operative Craig Williamson. Williamson denied it, and Swedish investigators could not substantiate the claim. Others tied the death to the Bofors arms scandal and the secret money moving through Cold War weapons deals. A persistent domestic theory pointed inward, at rogue elements of the Swedish police itself. Each had a motive that was genuinely plausible. None produced a confession or a document that held up.

The Skandia Man, named and un-named

On 10 June 2020, chief prosecutor Krister Petersson (no relation to the long-acquitted Christer Pettersson) held a press conference many Swedes expected to deliver an answer. He named Stig Engström, a graphic designer known as “the Skandia Man” because he had come from the offices of the Skandia insurance company near the scene, as the person he believed most likely shot Palme. And then he closed the case, because Engström had died in 2000 and could never be charged or tried.

The evidence was entirely circumstantial: Engström had been in the area, had some familiarity with firearms, moved in circles hostile to Palme, and roughly matched a witness description. There was no ballistic match, no confession, no physical proof, and no defendant left alive to answer any of it. Critics said the prosecutor had effectively declared a dead man guilty while making sure the claim could never be tested. In 2021 Sweden's Parliamentary Ombudsmenagreed in substance, finding that he had violated the presumption of innocence by presenting Engström as the murderer when guilt had never been established by any court.

The reversal came at the end of 2025. On 18 December, Sweden's director of public prosecutions, Lennart Guné, publicly withdrew the conclusion. He said plainly that there had not been enough evidence to name Engström, and that he should no longer be regarded as the main suspect. Guné pointed to witness accounts that made it doubtful Engström had time to carry out the shooting, to the absence of any explanation for how he could have known Palme would be on that street, and to the lack of any account of how he would have obtained the weapon. The state had named a suspect, and then the state had taken it back. The investigation stayed closed either way.

Where the evidence lands

On the core question, who killed Olof Palme and why, the verdict is Unproven, and it applies to every candidate equally. No theory (lone gunman, PKK, apartheid South Africa, the Bofors angle, or a police plot) has ever been substantiated to the standard of proof, and several have been actively undercut. The one person ever convicted was acquitted on appeal. The one suspect the state later settled on was withdrawn by the state's own chief prosecutor in December 2025. The murder weapon has never been conclusively matched to anyone.

It is worth being precise about what “unproven” does and does not mean here. It does not mean each theory is equally likely; the PKK line collapsed, and the Engström conclusion was formally repudiated. Nor does it endorse the darkest reading: much of what looks like conspiracy in this case is well documented as ordinary institutional failure, and honest observers should weigh incompetence heavily before reaching for a plot. What “unproven” means is narrower and harder. After forty years, the most exhaustive murder inquiry in Swedish history has not produced an answer that survives scrutiny, and the competing explanations remain exactly that: competing, and unproven. The file is closed. The question is not.