The two hit men, Max and Al, were not successful in killing Ole Andreson. They expected him to come to the restaurant where he supposedly ate dinner every night at six, but this night he didn't show up. They left town at the end. They wanted to kill him because they were being paid to do so by some unidentified man whom Ole told Nick he had double-crossed. There are many unanswered questions in "The Killers." Hemingway bragged that he had left out everything he could possibly leave out. At the end of the story, Ole is resigned to getting killed eventually and has given up trying to elude the man who wants him dead. Since Ole had been a professional boxer, it is likely that he double-crossed some mobster by deliberately losing a fight (taking a dive) when he was supposed to win, or winning a fight when he had agreed to take a dive.