Sweden has announced the relaunch of an investigation into the 1986 murder of its prime minister, Olof Palme, which is still a mystery despite countless leads.

Palme was gunned down in the street after leaving a Stockholm cinema with his wife, a killing that sent shockwaves through the country.

The gunman ran off with the murder weapon, leaving the charismatic Social Democratic leader dying in a pool of blood on the pavement. More than 10,000 people were questioned and 134 claimed responsibility for the crime but the case has never been solved.

Krister Petersson, a chief prosecutor notably for organised crime in Stockholm, will lead the new investigation. Petersson has tackled several major cases over a 20-year career, including the 2003 murder of the then foreign minister, Anna Lindh, who was stabbed to death in a department store by a man with psychiatric problems. Petersson will take up the new job in February, Sweden’s prosecution service said.

“I feel honoured and I accept the mission with a great amount of energy,” he said in a statement. “It is an interesting and important task.”

Petersson also handled the trial of John Ausonius, who shot 11 immigrants in the 1990s – some of them using a laser sight, earning him the nickname “Laser Man”. One of his victims died and Ausonius was sentenced to life in prison in 1994.

Petersson’s new case is a daunting one, with the files collected over the last three decades already taking up 250 metres of shelf space.

By coincidence, the prosecutor shares an almost identical name with the man convicted of the murder in 1989 – Christer Pettersson, a petty criminal and drug addict who was identified by Palme’s widow, Lisbet, in a widely criticised lineup.

He was freed months later by an appeals court that dismissed Lisbet’s testimony on a technicality, and died in 2004. He had admitted the murder before retracting his confession.