Besides the fact that the decision to prosecute someone is highly political, as is the decision not to prosecute, the decision to investigate and who investigates is also highly political.
Many federal agencies are at war with each other. Immigration and Customs Enforcement (ICE) is in the midst of a civil war, Customs versus Immigration; ICE is at war with DEA; DEA is at war with FBI; FBI is at war with ATFE; Customs and Border Protection (CBP) is at war with ICE; ICE is at war with its own mission; and U.S. Border Patrol is on its own mission, and no one knows what that is. And, of course, the U.S. Secret Service is playing its own game and has the President's ear, and a black SAC of the protective detail of the President. I wonder how that happened. And, of course, the FBI and Secret Service never work with each other. At least Obama is willing to put his life on the line for affirmative action.
The FBI, the primary investigative arm of the the United States, has recently been in the news about its ongoing war with the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATFE, formerly known as the Bureau of Alcohol, Tobacco and Firearm and the people who brought you Waco and Ruby Ridge). http://news.yahoo.com/s/ap/us_bomb_probes_feud;_ylt=ArkndYhKUGVIRXvL.1SY1NZH2ocA;_ylu=X3oDMTJtMTZkaXRxBGFzc2V0A2FwLzIwMDkwOTE2L3VzX2JvbWJfcHJvYmVzX2ZldWQEY3BvcwM3BHBvcwM3BHNlYwN5bl90b3Bfc3RvcmllcwRzbGsDZmJpYXRmZmV1ZGlu (h/t Of Arms and the Law
As usual, the FBI claims primary jurisdiction over all crime and terrorism specifically. However, ATFE is supposed to be the primary agency in matter of explosions, as well as the ever enjoyable alcohol, tobacco and firearms. I just call that fun. Unless of course, that explosion is committed in the furtherence of terrorism, then it is back in the FBI's court.
The dynamic was always funny, as in the old days the then ATF was a Department of Treasury agency and had a Treasury secretary to protect it. And the ear of the president once removed, as the USSS was also once a Treasury agency. As was Customs by the way.
However, 9/11 changed everything, except the unhappy dynamic among federal law enforcement. Hocus pocus, presto chango, agencies were moved around and things were supposed to be new and improved. DHS was created, Customs moved to DHS, Immigration moved to DHS, Secret Service moved from Treasury to DHS. Treasury was obviously the big looser, ATF to Justice and a name change to ATFE, Customs broken in half, the INS broken in thirds; It all stirred around and what did we have? Newer dynamic agencies dedicated to protecting America?
No, just a relaunch of old jealousies. The FBI always wanted to absord ATF and their conflict with ATFE has intensified as the FBI can just taste absorbing ATFE; CBP now jealous of ICE's monopoly on the obscure Office of Personnel Management definition of those who are allowed to investigate crimes because CBP was not allowed to have them, the infamous 1811 series in the long list of classification of federal employees, Criminal Investigators, AKA Special Agents, exept of course for the 1812 classification, Special Agent, Special Agents, of the Fish and Wildlife Service. In CBP they now have their 1811s but they are not 1811s, they are 1801s, another classification they call Special Agents. But according to OPM they are Investigative Program Specialists, and their poorer cousins, Marine Interdiction Agents and Air Interdiction Agents, both of those formerly Criminal Investigators, 1811, under Customs, but now reclassified to 1801. Interestingly enough identical to Deporation Officers, also 1801 and do similar work to the Criminal Investigators, 1811, who work for U.S. Citizenship and Immigration Services.
Confused yet? Don't be. The internicine jealousies reflected above also appear between the CIA and FBI, and gave us 9/11, as the CIA did not trust the FBI to find the two highjackers who were identified in Malaysia before that fateful day in New York, Pennsylvania, and Virginia. The CIA did not trust the FBI with all their info on two of the highjackers and the FBI did not want that information, hoping to find the two before any aid was offered from the CIA, and unwilling to actually take the action to find the two because Jorge Bush thought that Muslims were A-OK on 9/10. Not that that changed much, but we digress.
In any event, the lesson learned is that the Federal government is not interested in solving any criminal or terrorist problem, because doing so would require that federal agencies, many in the same departments, work to the same purpose, but that is not the acutal goal of those agencies. Protection of their turf is their most important goal, because that is how money and power from the Federal largess are budgeted.
So, if you think that the FBI, Fusion Centers, and the rest of the alphabet soup are concerned about your life and safety, think again.