Witness Disappears, Case Dropped

I thought this wasn't going to happen any more. There was a press conference, praise was heaped, concessions were made, tears were shed, etc. And this is the second time in a few weeks that the cases have been dropped because a witness a) couldn't be found or b) refused to testify. At what point does the FBI say, "Get the hell out of the way. We are taking over."? If Eddie Jordan can't convict this guy of murder, can't he convict him of something. They didn't get Al Capone on murder, they got him on tax evasion. Put this guy in jail and find a way to keep him there. Or let him out, tail him, and when he does something illegal back he goes.
These sorts of things make me embarrassed to be from New Orleans.