Anthony not guilty of murder

[Samurai Waki]

it was a three year investigation, no?

Time means for naught if you don't have anything to back up your case-- You can profile a murderer, speculate as to how the victim was killed, and what their motivation is-- but if you have nothing in the way of evidence to prove it, you simply don't have a case that can be proven beyond a reasonable doubt. A good example would be Gary Ridgeway aka The Green River Killer, law enforcement speculated for years that he was the one behind it, but they just couldn't get anything to stick-- finally after about five years they got a break in the case, a co-worker had collected a piece of his chewing gum-- and dropped it by the police department for evidence, they got his DNA and matched it with other DNA they had found on his victims, and they suddenly had the evidence they needed to convict him for Capital Murder.

Prosecution got overzealous, simple as that.

EDIT: Keep in mind she could actually be innocent.