(Reuters) - Federal prosecutors are developing a criminal fraud case hinged on whether General Motors made misleading statements about a deadly ignition switch flaw, and are examining activity dating back a decade, before GM's 2009 bankruptcy, according to multiple sources familiar with the investigation. At the same time, at least a dozen states are investigating the automaker. Two state officials said that effort is likely to focus on whether GM broke consumer protection laws. Both federal and state investigations into the switch, which is linked to at least 13 deaths and 54 crashes, are at early stages, and it is...