The abrupt decision Friday to shift the hunt for the missing Malaysia Airlines jet north about 700 miles was just the latest U-turn in a weeks-long investigation characterized by false hopes. Lead after lead has gone nowhere, clue after clue turned up empty — and partially to blame are international political squabbles, in a region rife with them. "This investigation is an example of what not to do," a former NTSB chair who presided over the TWA Flight 800 crash investigation told NBC News. Friday's shift was based on advice from Malaysian investigators whose new analysis of radar data found that the plane was flying faster than first thought and probably crashed earlier. Click through to read more about some of the leads that have dried up in the search.