This summer, when members of the Fort Worth City Council were briefed on the grim results of a federal investigation of the city's housing department, they could justifiably have asked the city manager and mayor, "What did you know and when did you know it?" The answer would probably have surprised them: Mayor Mike Moncrief and two successive city managers were aware of the department's deep financial problems for at least three years before federal investigators showed up in May 2008. Now, because those officials took no corrective action, the city is on the brink of losing most of the federal money it gets to help house its neediest citizens.