Forty years after Prime Minister Olof Palme was shot dead on a street in Stockholm, Swedes are still asking whether the killing was the work of a lone gunman or a political assassination.
The crime remains unsolved. Amateur detectives have now turned to artificial intelligence in the hope of identifying new clues and persuading authorities to reopen the investigation, which stalled in 2020.
The team behind the crime podcast Spår (Trail) has begun examining the main theories surrounding the killing with the help of an artificial intelligence tool developed for them by Swedish and Belgian software companies.
‘This is the murder of our leader, a democratically elected prime minister. The case cannot just be closed,’ said Anton Berg, one of the podcast’s hosts, who plans to present the findings generated with artificial intelligence step by step.
Spår has not yet announced any breakthroughs. Berg nevertheless pointed to the ability of artificial intelligence to learn and develop, saying, ‘We hope that this tool will improve enough that we will be able to reopen the investigation.’
A paradigm shift
Olof Palme was shot at close range on his way home from the cinema on 28 February 1986.
Over the years, suspicion has fallen on South Africa’s apartheid-era security services, Kurdish militants, right-wing extremists in Sweden and various lone gunmen.
One man was convicted but later released, and prosecutors closed the case in 2020. A review last year confirmed that the investigation would remain closed despite the main suspect having been cleared.
‘We basically know no more than we did on the day of the murder,’ said Gunnar Wall, who has written several books about Palme’s killing.
On the last day of February, marking the 40th anniversary of Palme’s death, protesters submitted a petition to parliament calling on the authorities to reopen the case. Such calls could gain support if amateur investigators are right in their belief that artificial intelligence can achieve what decades of police work have failed to do.
An artificial intelligence tool developed for the podcast Spår mimics a team of human investigators examining evidence, evaluating findings and identifying gaps, but it can do so much faster.
It has the ability to analyse around 30,000 publicly available digital case documents in less than a second. According to police estimates, reading the entire archive – roughly 500,000 pages – would otherwise take a decade.
From fingerprints to DNA profiling, forensic technology has repeatedly transformed criminal investigations. Experts say artificial intelligence could be the next game changer.
In 2018, DNA analysis using AI helped the Los Angeles Police Department identify Joseph DeAngelo, known as the ‘Golden State Killer’, a serial murderer and rapist responsible for at least 13 killings and more than 50 sexual assaults.
‘Artificial intelligence represents a paradigm shift,’ said Lena Klasen, former director of the Swedish National Forensic Centre and now professor of digital forensics at Linköping University.
‘It will change the way we work, just as computers did. But this is even bigger.’
Can AI provide answers?
Swedish police have declined to say whether artificial intelligence was used in the Palme investigation. The case will not be reopened unless there are strong grounds to believe that further inquiries could lead to an arrest and conviction.
Despite its ability to process vast amounts of data, AI may still struggle to identify Palme’s killer.
Case files are often heavily redacted and a large amount of material remains unpublished, said Simon Lundell, a member of an independent group of amateur investigators using AI in an effort to solve the case.
Access to police files is slow. Only about 1,000 pages are released each year. At that pace it would take centuries to review all the material.
Despite the obstacles, ‘our goal is to solve the murder,’ Lundell said.
There is also no guarantee that the evidence needed to solve the case still exists. Three public commissions concluded that the initial police investigation had been mishandled. Documents were lost and some leads were never pursued.
‘There is no technique that can help with information that does not exist. And that is a big problem, that there are gaps in the information,’ said Lennart Gune, director of the Swedish Prosecution Authority.
The growing use of AI in criminal investigations also raises concerns. The ‘Golden State Killer’ case triggered a heated debate about privacy after millions of people had their DNA data scanned without their explicit consent.
In 2025, Sweden proposed a law allowing police to use real-time facial recognition based on AI as a tool against gang crime. Its use, however, would be restricted because of concerns about privacy and surveillance.
(reuters, im)