My question: If the prosecution was competent, why did it take so long to bring charges?
Perhaps they were negotiating bribes and the deals fell through? Just a nasty speculation, for which I have no evidence. But it might be worth taking a look, if only to "clear their names".
My preferred assessment is that the DA office is filled with incompetent people who get by on plea-bargains for slam-dunk cases against criminals who cannot afford good defense lawyers. They could not decide what to do with a celebrity case who could get high-powered lawyers and publicity agents to mount an aggressive defense.