REYKJAVIK, Iceland — As chief of police in a tiny fishing town for 11 years, Olafur Hauksson developed what he thought was a basic understanding of the criminal mind. The typical lawbreaker, he said, recalling his many encounters with small-time criminals, “clearly knows that he crossed the line” and generally sees “the difference between right and wrong.”

Today, the burly, 48-year-old former policeman is struggling with a very different sort of suspect. Reassigned to Reykjavik, the Icelandic capital, to lead what has become one of the world’s most sweeping investigation into the bankers whose actions contributed to the global financial crisis in 2008, Mr. Hauksson now faces suspects who “are not aware of when they crossed the line” and “defend their actions every step of the way.”

With the global economy still struggling to recover from the financial maelstrom five years ago, governments around the world have been criticized for largely failing to punish the bankers who were responsible for the calamity. But even here in Iceland, a country of just 320,000 that has gone after financiers with far more vigor than the United States and other countries hit by the crisis, obtaining criminal convictions has proved devilishly difficult.

Public hostility toward bankers is so strong in Iceland that “it is easier to say you are dealing drugs than to say you’re a banker,” said Thorvaldur Sigurjonsson, the former head of trading for Kaupthing, a once high-flying bank that crumbled. He has been called in for questioning by Mr. Hauksson’s office but has not been charged with any wrongdoing.