Our legal system is built on the idea that all suspects are innocent until proven guilty. It is therefore the burden of the state to provide sufficient evidence that someone has clearly committed a crime. If the prosecution fails to find enough evidence, or as in this case, goes to trial before sufficient evidence has been found then the suspect (more times than not) goes free. In this case, the only evidence to support Casey killing her daughter was circumstantial at best. While I think there is a high likelihood that she did it (who else? did OJ sneak in and do it?) there simply is not enough physical proof to connect the dots with enough certainty to convince a jury.
At the end of the day, without any credible material witnesses, the prosecution cannot prove that a murder has occurred. At that point, they are left with a dead child who's demise was not reported for an excessive amount of time. This still plays into a conviction of wrong doing (as evidenced by the juries findings), but is much less satisfying for the grandparents in particular, but also the news-hungry mainstream media (as well as the rest of us ravenous devourers of current events).
At the end of the day, it is the news media that takes the blame for pushing this case to trial before a strong case could be built. With so much public outcry, the prosecution was forced to present a less-than-perfect picture of a horrifying criminal act that (had they had more time and less pressure) might have lead to a murder 1 conviction and a chance for Ms. Anthony to ride the lightning.
