My opinions only, no facts here:
To the mods- this post is relevant to the pending trial or trials in the Holly Bobo case. Read on.
I have followed criminal cases since the 1970's (if we only had the internet in the early days!). From the hundreds of cases I have followed to trial, I personally believe that if the jury is hung in the first trial, it should be over. End of story. You cannot be tried again IN ANY COURT. A more modern example of why I believe this: Raymond Lee Jennings. Check it out.
Think about what the defendants in a high-profile case such as this are facing. If there is a hung jury, they can be re-tried, for a million times if necessary (maybe in some states this is not true?), until the prosecutors can assemble 12 jurors who unanimously agree with a guilty verdict. What does this mean, in a philosophical sense? This is what it means: if all 12 jurors cannot find the defendant guilty, they are not guilty, BUT they are still "partly guilty" so they can be fully tried again and again until the "partly guilty" situation is resolved. This is completely illogical. IF by law it takes 12 jurors in agreement to have a guilty verdict, less than 12 jurors in agreement MUST be a not-guilty verdict. Remember, you cannot fall back on the return of the defendant to a "suspect" status after the hung jury, since they have been tried in court and the jury DID NOT CONVICT.
No double-jeopardy in the U.S., right? Let me show you how it really works. Here is my fictional but legally-factual thought experiment. A soldier from an army base, goes out on the town, gets drunk, and supposedly punches another drunk guy who is in a wheelchair and is making passes at the soldier's wife. No one in the bar actually sees the punch, but the guy in the wheelchair now has a black eye.
1) the soldier is charged with assault in criminal court by the city/state and after three hung-jury trials, the prosecutors give up.
2) the soldier is court-martialed by the military and found not guilty.
3) the Federal Government files civil-rights charges (based upon handicap of the man in the wheelchair) and after three hung-juries, the Feds give up.
4) the man is sued by the guy in the wheelchair and loses everything he owns in a civil trial (with its far lower standards of proof).
Quadruple jeopardy at this point, with a lot more than four separate trials!
Now, if the man in the wheelchair were a foreigner, and the U.S. was willing to extradite, it might be possible to be tried again in a foreign court. This is quintuple jeopardy.
I am working on a sextuple jeopardy thought experiment. This requires that the guy in the wheelchair has some international prominence, where an international court could be involved.
Other than entertaining my friends here at Websleuths, my point is this: if you do not have star-power defense (someone like Jose Baez), you will always be at a severe disadvantage to the prosecution in the many trials you may ultimately face. Is it any wonder that there are so many "no-contest" pleas and plea-bargains?
I am not just pontificating here. I will review my files on the Holly Bobo case for someone who actually fits the FBI description.