Perry, who like everyone associated with the captivating months long trial in 2011 has become something of a celebrity, told NBC's "Today" Monday he thought prosecutors had made a strong enough case against Anthony.
"I thought they had proved a great case, but you've got to realize this was a circumstantial evidence case," Perry said. "All the defense had to do was create that reasonable doubt, and that's what they did."
Perry said Anthony manipulated the jury and her demeanor changed significantly when jurors were out of earshot.
"There were two sides to Casey Anthony," Perry said. "There was the side that was before the jury, where she portrayed the role of a mother who had lost a child, someone who was wrongfully accused, and then you could notice the change and transformation in her when the jury went out."
Anthony was accused of killing Caylee, whose remains were found in a wooded area near her home. Jurors acquitted her of the first-degree murder charge in July 2011.
Perry credited Anthony's lawyer, Jose Baez, for developing a rapport with the jury that helped exonerate his client.
"The state had better lawyers, but Mr. Baez was very personable," Perry said. "He came across as someone that you would like. It's like someone trying to sell a used car. Who are you going to buy it from? The most likable salesperson."