A top FBI agent yesterday urged people who "knowingly or unknowingly" played a role in last October's slaying of federal prosecutor Thomas Wales to reveal themselves. "There is reason to believe that there are people who have knowledge of this homicide," said Charles Mandigo, special agent in charge of the Seattle FBI office. "It is time for them to come forward." Asked whether agents are looking for an accomplice, such as someone who may have driven the killer to or from the scene, Mandigo said the suspected involvement was "of that general nature, yes." The statement was the most substantive...