From my understanding of the Florida statutes the sentences for the drug charges are mandatory minimum sentences. That means anyone sentenced under them is not eligible for early release. Any offer like that would've been done before trial. Instead of Florida taxpayers pay nearly 7.5 million to keep just Misty confined for 25 years, authorities would be better served to stick it to her by actually finding evidence, charging her, and proving it at trial.
I've always been of the opinion that neither Misty or Ron know for sure what occurred. Ron because he was at work, and Misty because she was either not in the home or was asleep. They may have ideas, or suspicions which may explain why their lie detector results could be all over the place (not that lie detectors are worth a damn anyway). Misty was facing 6 to 100 years in prison of guaranteed time. An 18 year old with no reliable family, little education, drug issues, would've likely spoke up at that point if she had something firm to give. These aren't hardcore mafiasos with a code of silence.