HELSINKI - Swedes on Sunday marked the 30th anniversary of the murder of Prime Minister Olof Palme, which shocked the nation out of its innocence and is still baffling investigators.

The day's remembrance began with Social Democratic Prime Minister Stefan Lofven laying a wreath at Palme's grave in the Swedish capital and people placing flowers on the street corner in central Stockholm where Palme was gunned down as he left a cinema late on a Saturday night on Feb. 28, 1986.

Immediately after he was killed 30 years ago, thousands of shocked Swedes flooded the scene of his death with red roses, a symbol of Palme's Social Democratic Party, building a meter-high wall of flowers.

Get Breaking News Delivered to Your Inbox

The murder spoiled the Scandinavian county's image as a nation so safe and peaceful that politicians could wander around in public without protection. Another later painful reminder of Sweden's lost innocence came in 2003, when Foreign Minister Anna Lindh was stabbed to death in a Stockholm department store, also without bodyguards.

In the days leading up to Sunday's 30th anniversary, local media have been filled with stories about the life and political career of one of the most charismatic Swedish leaders to date.

Palme, who cut a flamboyant, even boyish figure, had an aristocratic backgound but was known for his left-leaning views and was eyed with suspicion in conservative circles and by the United States. Among Swedes and in the Nordic region, he was much loved, but also hated.

On the fateful night, Palme had given his bodyguards the night off and was walking home with his wife when the killer shot him twice in the back and then escaped down a dark alley.

The only man tried for the murder, an alcoholic and drug addict named Christer Pettersson, was acquitted on appeal after police failed to produce any technical evidence against him. Pettersson died in 2004.

More than 100 people have been suspected of the crime and the unsolved case has been surrounded by conspiracy theories. Having rejected thousands of earlier tips, investigators on Sunday opened a hotline, appealing to the public for possible new clues to help solve the assassination.

Events were planned nationwide, with a special memorial program later Sunday at a cultural center in Stockholm.