In his final opportunity to speak to the 12 jurors, who sat stone-faced, attentive and unreadable throughout the trial's intense six weeks, defense lawyer Jose Baez told them that the biggest question of all, how Casey's 2-year-old daughter Caylee died, remained unanswered.
"It can never be proven," he said.
In the end, the jury agreed. But why?
Several Key FactorsLegal experts say the stunning not-guilty verdict is a result of several key factors, beginning with the lack of hard evidence tying Casey, 25, to the crime.
Prosecutors said Casey applied duct tape to Caylee's nose and mouth to kill her; Baez said the little girl drowned in the Anthony family swimming pool, an accident that was then covered up by Casey's father George. (After the verdict, George and Cindy Anthony deemed her defense "baseless.")
"The prosecution had a theory that Caylee was suffocated," says longtime Orlando criminal defense attorney Michael Dicembre. "The reality is, it was a theory. Nobody could say how Caylee died, when she died. We don't know."
Adds local defense attorney Richard Hornsby: "The bottom line is that the jurors did not completely believe the prosecution's theory and they chose to acquit. They were able to raise reasonable doubt in the jurors' minds."
What's more, Baez's repeated insistence that Caylee's death was "an accident that snowballed out of control" seemed to ring true with jurors, who were presented with extensive testimony regarding the Anthony family's dysfunctional dynamic.
"It was such a horrific accident, they didn't know how to deal with it," alternate juror Russell Huekler told HLN. "The family appeared to be very dysfunctional and instead of admitting ... there was an accident, they chose to hide it for whatever reason."
Huekler also said he found the evidence regarding the smell in Casey's Pontiac Sunfire unconvincing, despite testimony from multiple witnesses – including Casey's mother Cindy – that the car reeked of death.
"You have to remember there were a number of law enforcement officers that responded to July 15 and none of them smelled the odor," Huekler told HLN. "It was hard for me to accept that there had been a body in the car."
'Evidence, Not Emotion'From the start, the prosecution seemed to possess a strong, if circumstantial, hand: The smell of a dead body in Casey's trunk. A hair from Caylee, which forensic evidence tied to a decomposing body. Incriminating computer searches for "chloroform" and "neck breaking." Thirty days of the defendant's partying and lying in the wake of her daughter's disappearance.
And the underdog defense team? They built their case around their client's lies. Her "imaginary friends." Accusations, unproven, of sexual abuse at the hands of her father George.
But with the burden of proof resting squarely on the prosecution, Baez hammered that point that his client's extensive lies didn't prove her guilt.
"Just because she lied doesn't necessarily mean she committed the murder," says Dicembre. "I really think the jury in this case tried to remove the emotion, as Baez asked them to. They made a decision simply based on the evidence presented, not emotion."
Still, Baez managed to pull off a rare feat: He sharply changed direction after his explosive opening arguments, backing off of the sexual abuse claims without losing the jury.
"He really seemed to paint himself into a corner with that opening statement," says Dicembre. "The fact that he was able to get a not guilty ... he shot a lot of traditional thought right out of the water."
Unpredictable JuryOne thing that legal experts on both sides agree upon: Juries are invariably unpredictable.
Not permitted to discuss the trial even among themselves until deliberation, the sequestered Anthony jury was completely cut off from the constant chatter about the trial, CNN's Nancy Grace's "tot mom" rage and the millions of trial watchers who thought Casey was guilty.
"When you've been doing this for so long, you know that you never know what a jury will do," says Orlando defense attorney Bill Umansky, who closely followed the case.
"The bottom line is, the prosecution did a good job, but circumstantial cases are very difficult to prove," adds Umansky. "What happened to Caylee? We may never know."
Despite public outcry over the verdict, "This is the jury system," says Hornsby. "The whole point is that a jury of one's peers makes the decision, not the government. Casey Anthony had her trial, and the jury made its decision. We have to accept it."
With reporting by STEVE HELLING