STOCKHOLM (Reuters) - Sweden may soon get closure over the 1986 murder of Prime Minister Olof Palme after the lead prosecutor said he would either bring charges in the coming months or close the case.

FILE PHOTO: Roses are shown laid on a plaque on a street in Stockholm on Feb. 28, 2011, marking the location where Swedish Prime Minister Olof Palme was shot and killed on Feb. 28, 1986. REUTERS/Bob Strong/File Photo

Palme was gunned down in central Stockholm in February 1986 after an evening at the cinema with his wife. His death sparked Sweden’s biggest ever manhunt and a slew of conspiracy theories.

A nagging sense of unease remains over the police’s failure to catch his killer, but prosecutor Krister Petersson held out hope that the case could be solved, saying he was close to wrapping up the investigation.

“We are now working on avenues that are very interesting and my goal is that during the first half of 2020 we will be able to make a decision on whether to prosecute,” Petersson, head of the Palme investigation, told Swedish TV programme ‘Crime Week’.

“I still feel positive that we will be able to present what happened on February 28, 1986. What happened at the time of the murder and was who was responsible,” Petersson said.

He said it was possible that the investigation would be closed without a prosecution. That could happen, for example, if the suspect were already dead.

The prosecutor’s comments triggered renewed speculation about the killer’s identity and whether Petersson has been able to unearth new evidence after so many years - potentially the gun used in the murder, which has never been found.

Palme, a Social Democrat, was Sweden’s prime minister between 1969 and 1976 and again between 1982 and 1986. Hated by conservatives for his anti-colonial views and criticism of the United States, some Swedes even believed he was a KGB spy.

His murder has been variously blamed on Kurdish separatists, the South African security services and the Yugoslav secret police as well as a right-wing cabal in Sweden.

A petty criminal, Christer Pettersson, with a previous conviction for stabbing a man dead with a bayonet, was found guilty in 1989 of Palme’s murder only to be freed on appeal. He died in 2004.