There are many reasons why federal investigations might take some time to conclude. Perhaps the issues are complex. Maybe the parties under investigation are less than forthcoming. The investigating agency may lack the resources needed to resolve the matter in a timely fashion.
On the other hand, a stalled investigation may be part of a crisis management strategy. When an embarrassing ethical or legal transgression surfaces, launching an investigation sends the message that the matter is being taken seriously. Thanks to a rapid news cycle and a lack of follow-up reporting, public attention shifts elsewhere as the investigation continues. Closing the investigation can be seen as counter-productive, as it once again calls attention to the problem and creates the expectation that the findings will be acted upon.
Representative John Dingell (D-Mich.) may well have been pondering such matters on March 14, when he pointedly asked Federal Communications Commission Chair Kevin Martin about the status of the agency's ongoing Armstrong Williams investigation.